Dumb Data: Legal Doctrines & Principles

NOTE: I am not a lawyer, just someone who is making sense of the law for people who don’t understand it. Do not use this as legal advice.

Law is defined by many precedents, mostly through previous cases that created rulings. These cases create a framework of philosophical thought that forms a legal maxim over time. Most attorneys tends to learn these maxims and doctrines in law school, thereby reinforcing its culture.

Even in a fledgling nation, many lawyers will consult other nations that wrestled with the same issues instead of starting from scratch.

Human nature is relatively unchanging, so laws seem to always have some overlap, even across vastly different cultures. It is worth indicating, however, that some of these doctrines are actually unethical in many situations.

Broad Maxims

Boni judicis est ampliare jurisdictionem – A good judge will enlarge his jurisdiction (i.e., remedial non-binding authority)

Furiosis nulla voluntas est – A madman has no will

Furiosis furore suo puiner – A madman is best punished by his own madness

Furious absentis loco est – A madman is like someone absent

Actio personalis moritur cum persona – A personal right of action dies with the person

Pacta sunt servanda – Agreements must be kept

Actus non facit reum nisi mens sit rea – An act does not make one guilty unless it is accompanied by a guilty mind

Actus me invito factus non est mens actus – An act done by me against my will is not my act

Pacta sunt servanda – Agreements must be kept

Volenti non fit injuria – Damage suffered by consent gives no cause of action

Lex non a rege est violanda – Even the king must not violate the law

Everything which is not forbidden is allowed

  • More specific times: Everything which is not allowed is forbidden

Falsus in uno falsus in omnibus – False in one thing, false in everything

Audi alteram partem – Hear the other side

Ignorantia facit doth excusat, Ignorance juris non-excusat – Ignorance of fact is an excuse, but ignorance of the law is no excuse

Fraus est celare fraudem – It is a fraud to conceal a fraud

Interest reipublicae ut sit finis litium – It is in the republic’s interest that there be an end to litigation

Justice delayed is justice denied

Justitia nemini neganda est – Justice must be denied to nobody

Necessitas non habet legem – Necessity knows no law

Nemo dat quod non habet – Nobody can give what they don’t have

Nemo debet locupletari ex aliena jactura – Nobody should grow rich from another’s loss

Nullum crimen sine lege, nulla poena sine lege – No crime without written law, no punishment without written law

Nemo moriturus praesumitur mentire – No dying person presumes they can lie (implies dying declarations have weight)

Nemo iudex in causa/propria sua – No one is judge in their own cause

Nemo Potest esse tenens et dominus – No person of a property can be both tenant and landlord

Nemo plus luris ad allum transferre potest quam ipse habet – One cannot transfer to another more rights than they have

Qui facit per alium facit per se – One who acts through another does the action themself

Qui peccat ebrius luat sobrius – One who does wrong while drunk must be punished while sober

Qui sentit commodum, sentire debet et onus – One who receives the advantage must also bear the burden

Res inter alios acta, aliis nec nocet nec prodest – Something done between some can’t harm or benefit others

Actori incumbit onus probandi – The burden of proof is on the plaintiff

Potior est conditio possidentis – The condition of the possessor is better

Rex non protest peccare – The king can do no wrong

Salus populi est suprema lex – The people’s welfare is the supreme law

De minimis non curat lex – The law does not govern unimportant things

Communis hostis omnium – They are common enemies of all

Violenti non fit injuria – To a willing person, injury is not done

Ubi jus ibi remedium – Where there is a right, there is a remedy

General Law Doctrines

Absolute liability (tort and criminal law) – an entity is liable for an action irrespective of their intent, views, or feelings

Actio libera in causa (civil and common law) – Latin for “action free in its cause”, even if someone wasn’t free to choose the course of action that violated a law or contract, they can still be held responsible if they voluntarily created a condition (“cause”) for the offending action

Actionable per se – The very act is punishable, and no proof of damage is required

Ademption by satisfaction – aka “satisfaction of legacies”, when someone gives part of their inheritance to their trustee before they die, it’s considered an advance payment

Administration of justice – every government gives its judges authority under several possible systems:

  • Civil law – going back to Roman law, a code passed by a legislature that judges interpret
  • Common law – the judges’ decisions determine the source of the laws
  • Religious law – a religious system or document is the legal source, typically for a monotheistic religion
  • A hybrid combination of the above

Alternative liability – even when one defendant may be at fault, the plaintiff can shift the burden of proving causation of their injury to multiple defendants

Attribution – aka “Imputation”, a broad family of legal doctrines where a defendant is liable who didn’t actually commit a criminal act (e.g., attempt/conspiracy to commit a crime, even if it wasn’t performed)

  • Carltona doctrine (UK law) – the acts of government department officials are the same as the actions of the minister in charge of that department
  • Command responsibility – aka “Yamashita standard”, “Medina standard” or “Superior responsibility”, a commanding officer (military) or superior officer (civil) is legally responsible for the war crimes and crimes against humanity committed by their subordinates
  • Respondeat superior (common and civil law) – Latin for “let the master answer”, aka “vicarious liability” or “master-servant rule”, where employers/guardians/owners are responsible for the decided acts of their subordinates/dependents/charges
  • Enterprise liability – individual entities like legally unrelated corporations or people can be held jointly liable for an action on the basis of being part of a shared enterprise

Beneficium inventarii – literally “benefit of the inventory”, limits liability of heirs when an estate becomes insolvent

  • Doctrine of exoneration of liens (common law) – a debt of a property (i.e., a mortgage) is paid with funds from the originating estate and not from the property itself

Bona fide purchaser (common and property law) – Someone who buys property without knowing that someone else different than the seller had rightful ownership to it is entitled to receive it

Chances doctrine – evidence is permitted to show that it is unlikely a defendant would be repeatedly, innocently involved in similar suspicious circumstances

Clean hands doctrine – aka “unclean hands doctrine” or “dirty hands doctrine”, a plaintiff is not entitled to obtain an equitable remedy if the defendant has proof they were acting unethically or in bad faith (e.g., monopolizing)

Commanding precedent – when the facts and issues of a previous case’s ruling are nearly the same, the previous ruling takes precedence

Contra principia negantem non est disputandum – Latin for “against one who denies the principles, there can be no debate”, to debate reasonably about a disagreement there must be agreement about the principles or facts that judge the arguments

Desuetude – a law that’s been valid but unenforced for a long time (e.g., obsolete) doesn’t have much weight in a ruling

Eminent domain – aka “land acquisition”, “compulsory purchase/acquisition”, “resumption”, or “expropriation”, a government has the right to take private property for public use

Equity – a broad concept developed within the English Court of Chancery meant to provide a remedy where certain situations make the law to inflexible to create a fair resolution to a case (i.e., courts of equity allow for one-off weird situations)

Erga omnes – Latin for “towards all/everyone”, an enforceable right or obligation owed toward everything else

Ex post facto law – Latin for “out of the aftermath”, a law will retroactively change the legal consequences or status of actions that were committed before that law came into existence

Floodgates principle – in certain situations, if a judge were to rule for claims for damages, it would open metaphorical “floodgates” to large numbers of claims and lawsuits

Furiosi nulla voluntas est – Latin for “a madman cannot voluntarily choose”, mentally impaired people cannot validly sign a will, contract, or form a frame of mind necessary to commit a crime.

Homestead principle – when something is unowned, someone gains ownership of it by performing an act of original appropriation

In loco parentis – Latin for “in place of a parent”, a person or organization is sometimes legally responsible to take on some of the functions and responsibilities of a parent

In pari delicto – Latin for “in equal fault”, when both parties in a civil action are equally at fault or when the plaintiff has greater culpability, the court will not get involved in resolving one side’s claim over the other

  • Wagoner doctrine – a claim of defrauding a willing corporation by a third party accrues to the creditors, and not to the guilty corporation

Interpretation rules – there are several ways to interpret laws in a court:

  • Plain meaning rule – the statutes should be taken word-for-word and interpreted according to the original meaning of the language, the mechanism for textualism (that the original meaning of the law supersedes) and some parts of originalism (that the original understanding of the law as it was framed applies)
  • Mischief rule – the statutes should not only consider the exact wording of a rule, but also the legislators’ intentions for enacting it to determine if a rule applies
  • Golden rule – the statute as a textual whole provides context on how a given provision should be interpreted when resolving textual difficulties, can be a “narrow approach” (where the interpretation is really scoped down to specifics) or a “broad approach” (where it simply avoids any absurd results of precise and impractical law)

Jurisprudence constante – French for “stable jurisprudence”, a series of previous decisions that applied a previous legal principle or rule is highly persuasive but not controlling in subsequent cases dealing with similar or identical legal issues

Laches – French for “latches”, if a plaintiff has “slept on its rights” and there is an unreasonable delay to change circumstances to make it harder for the plaintiff to prove their case, it’s no longer a just resolution to grant the plaintiff’s claim

  • Acquiescence – when a person knowingly stands by without raising objection to the infringement of their rights while someone else infringed on those rights unknowingly and without premeditated malice, that person may lose the right to take legal action against the infringer
  • Nullum tempus – Latin for “no time runs”, short for “nullum tempus occurrit regi” or nullum tempus occurrit reipublicae” (no time runs against the king/republic), the government can proceed with actions that would normally be barred by laches, removes the complete legal inpenetrability of “squatters’ rights”

Last antecedent rule – if there’s a comma, it dramatically separates concepts in the text, one of the pettiest law disputes in existence

Legal certainty – a law must allow people to make decisions to regulate themselves within it

Land tenure doctrine – land owned by an individual is possessed by someone who “holds” the land due to an agreement (i.e., feudalism)

Male captus, bene detentus – Latin for “wrongfully captured, properly detained”, a person may have been wrongfully or unfairly arrested but it won’t affect whether that person’s trial can be fair

Mater semper certa est – Latin for “the mother is always certain”, the mother of the child is conclusively established, from the moment of birth, by the mother’s role in the birth (somewhat more complicated with in vitro fertilization)

  • Pater semper incertus est – Latin for “the father is always uncertain”, the father of the child is never clearly defined
  • Pater est, quem nuptiae demonstrant – Latin for “the father is he to whom marriage points”, being married can clarify who a child’s father is (though DNA testing is now often more effective)

Merger doctrine – one of several doctrines depending on the domain:

  • Merger doctrine (civil law) – when litigants agree to a settlement, then seek it incorporated into a court order, that court order extinguishes the settlement and the authority of the court supervises behavior of both parties
  • Merger doctrine (copyright law) – a clarification to idea–expression distinction where sometimes both the idea and expression are seen as merged, meaning the expression can’t be protected (prevents double jeopardy)
  • Merger doctrine (criminal law) – lesser included offenses tend to merge into the greater offense
  • Merger doctrine (family law) – a woman’s legal identity merges with her husbands, meaning she couldn’t sue or testify against him (largely outdated)
  • Merger doctrine (property law) – the contract for conveying proerty merges into the deed of conveyance, so any contractual guarantees not made in the deed are extinguished when the deed is conveyed
  • Merger doctrine (trust law) – when the same person is both the sole trustee and sole beneficiary of a trust, the legal and equitable title are fused and the trust is sometimes deemed to have terminated

Nolle prosequi – Latin for “to be unwilling to pursue”, prosecutors can end a criminal case before trial or before a rendered verdict

Non bis in idem – Latin for “not twice in the same thing”, aka “nemo bis punitur eodem delicto (nobody can be twice punished for the same offense), a Roman law where no legal action can be instituted twice for the same cause of action

Non-aggression principle – any act of aggression is inherently wrong

Novus actus interveniens – Latin for “new intervening act”, aka “breaking the chain”, in a cause-and-effect situation, an independent event which breaks the chain of events between the defendant and the imputed action

Nulla poena sine culpa – Latin for “no punishment without fault”, someone cannot be punished for something they are not guilty of

Onus probandi – Latin for “burden of proof”, one side of a dispute is typically presumed to be correct and the other side (typically the prosecutor/claimant) must provide evidence against the defendant

Open court principle – court proceedings must be open and accessible to the public, especially the media

Open justice – judicial proceedings must be conducted transparently and with the oversight and scrutiny of the people

Public policy doctrine – there are certain principles underneath all societies, though their implementation may vary:

  • Ignorantia juris non excusat – Latin for “ignorance of the law is not an excuse”, frames the legal fiction of “constructive notice”
  • Sanctity of life – life has enough inherent value that there is no clear justification to end a life except when in mortal self-defense
  • Evasion doctrine – people and entities can’t evade the obligations and liabilities attached to them
  • Parens patriae – Latin for “parent of the nation”, the state can intervene against an abusive or negligent parent, guardian or caretaker
  • Favor matrimonii – Latin for “preferred marriage”, a marriage should be considered valid unless specific situations indicate otherwise

Proportionality – the scope of repayment/restitution/punishment should fit the damages/crime

Reasonable person – aka “reasonable man” or “man on the Clapham omnibus”, a hypothetical reasonable person who possesses a common set of facts and makes conclusions about what they observe, used for interpreting how a case should be ruled when the facts are incomplete to make a conclusion

Res judicata (civil and common law) – a case that delivers a final judgment can’t be subject to appeal any longer and that judgment continues to hold weight, similar to double jeopardy and non bis in idem

Rule according to higher law – a government can only enforce a law if it conforms with universal principles of fairness, morality, and justice

Rule against perpetuities – people who own legal instruments (e.g., trust, will) cannot exert control over private property for a long time beyond the lives of people living when the instrument was created

Slippery slope – making a ruling in a small matter can profoundly affect a larger one later

Statute of limitations – there is a set amount of time after an event happens where a case can be filed

  • Tolling – the period of time for a statute of limitations can be paused for a variety of specific reasons

Strict liability – a person is still legally responsible for the consequences flowing from an activity, irrespective of fault or criminal intent

Substantial certainty – even if someone didn’t intend a result, they are still responsible for it if they knew it was a reasonable likelihood

Tender years doctrine – mothers should have custody of children under ~4 years old

Undue influence – an action can be set aside for proceedings if that person was being extremely influenced/coerced by someone else

Year and a day rule – a person’s death can’t be attributed to an action that was more than a year and a day ago


Best interests – aka “best interests of the child”, a child right principle that indicates that the best interests of a child should be the primary consideration in a ruling


Aggregate effects doctrine – aka “substantial effects doctrine” or “cumulative effects doctrine”, interstate commerce regulations can affect any action only if it’s combined with other legal actions

Ecclesiastical abstention doctrine – legal systems can’t act on behalf of or against protected religious expression

Intracorporate conspiracy doctrine – members of a corporation can’t be held to have conspired among themselves, since the corporation is a single actor for the purposes of law, which means a conspiracy can include 1 actor

Undue hardship – specific circumstances can make someone exempt from particular responsibilities

Warranty tolling – in California, product warranties must sometimes be paused for the advantage of the purchaser

Willful blindness – if someone tries to avoid criminal liability by intentionally keeping themselves unaware of facts, they still know what they’re doing


Equal authenticity rule – both versions of a bilingual law (English and French) are equally authoritative

Wahkohtowin – Cree for “kinship”, every interaction has a social impact, typically represented by various circles of influence


Spring and Autumn Courts – judges determine their convictions based on their ideas of righteousness from the Spring and Autumn Annals (2,500-year-old legal documents that span a 350-year timespan further back)

Criminal Court Doctrines

Abatement ab initio – Latin for “from the beginning”, the death of a defendant appealing a criminal conviction stops all criminal proceedings initiated against that defendant

Beyond reasonable doubt – aka “moral certainty” a legal standard of proof commonly used in criminal court that indicates there must be irrefutable proof to validate a conviction, contrast to balance of probabilities

Crimen trahit personam – Latin for “the crime carries the person”, aka “interterritorial jurisdiction”, a series of crimes across jurisdictions carry broader penalties

Due process – there are procedural rules and principles established by the state that honors the law of the land while also protecting the individual from the state

Fruit of the poisonous tree – evidence (“fruit”) obtained by illegal means (“poisonous tree”) is inadmissible in a court as evidence

  • Inevitable discovery – an excepton to exclusionary rule and fruit of the poisonous tree: admission of illegal evidence is still permissible if it would have “inevitably” have been obtained regardless of the legality

Hub-and-spoke conspiracy (criminal and antitrust law) – several parties (“spokes”) can enter into an unlawful agreement with a leading party (“hub”)

Jus necessitatis – Latin for “just necessity”, aka “doctrine of necessity”, a charged defendant should not be held responsible if they were performing a crime that prevented a greater harm

Legality principle – no one can be convicted of a crime without a previously published legal text that clearly describes the crime

Negotiorum gestio – someone who acts on behalf of another’s interests (the “gestor”) without that person’s permission is entitled to reimbursement, but not remuneration

Nulla poena sine lege – Latin for “no punishment without law”, someone cannot be punished for something that isn’t prohibited by law

  • Nulla poena sine lege praevia – Latin for “no punishment without previous law”, meaning ex post facto laws are prohibited
  • Nulla poena sine lege scripta – Latin for “no punishment without written law”, meaning the laws must be written and not merely spoken
  • Nulla poena sine lege certa – Latin for “no punishment without well-defined law”, meaning the punishable conduct and penalty must be clarified with sufficient definiteness
  • Nulla poena sine lege stricta – Latin for “no punishment without exact law”, meaning application by analogy is prohibited

Presumption of guilt – the defendant is guilty when the evidence is uncertain and they possess the burden of proof, prioritizes speed and efficiency over reliability and can be a violation of human rights

Presumption of innocence – the defendant is innocent when the evidence is uncertain and the plaintiff possesses the burden of proof, tends to favor human rights but can be much slower proceedings

Prosecutorial discretion – public prosecutors have a wide latitude to decide whether or not to charge a person for a crime and which charges to file

Totality principle – after sentencing has been counted but before delivering it, measure it by adding it all together to make sure it’s fair and accurate

Transferred intent – aka “transferred mens rea” or “transferred malice”, if someone intentionally tries to harm someone else, but harms a third person, they’re still responsible

Typicality (criminal law) – aka “prohibition of analogy”, criminal law only applies to real events that actually relate to the abstract case, without having to use an analogy

Year and a day rule (criminal law) – a crime is counted as a felony if the sentencing is at least a year and a day


Brady disclosure – the prosecution is required to disclose any information or evidence that’s material to the guilt, innocence or punishment of a defendant

Castle doctrine – a person has protections and immunities that permit them to use force to defend their legally occupied place from intrusion

Dangerous proximity doctrine – preparing and attempting a crime don’t form a clear standard, so preparatory acts are considered stronger evidence of action if the offense is more probable and more grave or serious, mixes with physical proximity doctrine

Double jeopardy – an accused person cannot be charged again on the same (or similar) charges following an acquittal or conviction, similar to res judicata and non bis in idem

Duty to retreat – aka “requirement of safe retreat”, a threatened person cannot harm another in self-defense when it’s possible instead to retreat to a place of safety, contrast to stand-your-ground law, dovetails often with castle doctrine

Exclusionary rule – evidence collected or analyzed in violation of a defendant’s constitutional rights can’t be used in a court of law, validates the 4th Amendment

  • Good-faith exception – an exception to exclusionary rule: evidence can be admitted if it’s collected in violation of an individual’s constitutional rights but the police officer believed their actions were legal
  • Independent source doctrine – an exception to exclusionary rule: evidence initially discovered during or in the course of an unlawful search can still be lawful if it was later obtained independently by lawful activities later
  • Mosaic theory – for assessing 4th Amendment violations (i.e., privacy violations), a government bureau’s information collection is treated as an aggregate “mosaic” rather than on an individual per-agency or per-investigator basis
  • Open-fields doctrine – a search without a warrant of the area outside a property owner’s dwelling and immediate area doesn’t constitute a violation of the 4th Amendment
  • Plain view doctrine – an exception to exclusionary rule: an officer is permitted to seize evidence and contraband found in plain view during a lawful observation
  • Third party doctrine – people who voluntarily give information to third parties (e.g., banks, phone companies, email servers, internet service providers, social media companies) have no reasonable expectation of privacy of that information, so governments don’t need a warrant to obtain it

Fleeing felon rule – it’s lawful to use force (including deadly force) against an individual suspected of a felony and clearly fleeing

Massiah doctrine – A confession obtained without a defendant’s right to counsel (i.e., elicited by the police directly from them) is inadmissible in a court, holds up the 6th Amendment

Physical proximity doctrine – preparing and attempting a crime don’t form a clear standard, so preparatory acts are considered stronger evidence of action if the preparatory act is physically closer to the completed crime, mixes with dangerous proximity doctrine

Stand-your-ground law – aka “line in the sand” or “no duty to retreat” law, people may use deadly force when they reasonably believe it necessary to defend against certain violent crimes, contrast to duty to retreat


Nuremburg principles – there are guidelines to define a war crime:

  1. Any person who commits a crime under international law is responsible for it.
  2. Even if internal law does not impose a penalty for a crime under international law, the person is still held responsible for that violation.
  3. Being in an official government capacity does not relieve them from responsibility under international law.
  4. A person acting on behalf of a superior or their government does relieve them of responsibility under international law.
  5. Anyone charged with a crime under international law has the right to a fair trial on the facts and law.
  6. There are several crimes punishable under international law:
    • Crimes against peace – planning, preparing, initiating or waging a war of aggression or in violation of international treaties, agreements, or assurances, or simply participating in a common plan or conspiracy for it
    • War crimes – includes murder, ill-treatment or deportation to slave labor in occupied territory, mistreatment of prisoners of war, killing hostages, plundering public or private property, heavily destroying cities and other community locations, and devastating anything not justified by military necessity
    • Crimes against humanity – murder, extermination, enslavement, deportation, persecutions on political/racial/religious grounds
  7. Complicity with any of the crimes stated above is still violating international law.


María Clara doctrine – aka “Woman’s Honor doctrine”, women, especially Filipinas, would not admit they had been abused unless that abuse actually happened

Civil Court Doctrines

Arm’s length principle (contract law) – the parties of a transaction must be independent and on equal footing

Assumption of risk (tort law) – a defense that a defendant is not liable for risks that the plaintiff knowingly ignored, can be express or implied

Attractive nuisance doctrine (tort law) – a landowner may be held liable for injuries to children trespassing on their land if the injury is caused by an object on the land that’s likely to attract children

Balance of probabilities – a legal standard of proof commonly used in in civil court that indicates that the ruling will decide based on what party’s claim is most probable when considering all the factors, contrast to reasonable doubt

Blue pencil doctrine (contract law) – if a contract has unenforceable components, its enforceable parts are still legally valid

Caveat actor – Latin for “let the doer beware”, the person performing the action is responsible for their action.

Caveat emptor (contract law) – Latin for “let the buyer beware”, the buyer must be aware of specific details pertaining to who they’re buying from and the product they’re buying

Caveat lector (contract law) – Latin for “let the reader beware”, the reader should take careful note of a text’s contents and undertake due diligence on whether the contents are accurate, reliable, relevant, etc.

Caveat venditor (contract law) – Latin for “let the seller beware”, the seller must be aware of specific details pertaining to who they’re selling to and why

Clausula rebus sic stantibus (contract law) – Latin for “as things stand”, a contract or treaty becomes inapplicable because of a material change in circumstances, counter-balances pacta sunt servanda

Clayton’s case – debts to a bank must be paid in the order they were incurred

Collateral source rule (common law) – evidence that the plaintiff/victim has received payment from a source other than directly from the defendant is inadmissible, which allows for double recovery against the defendant (e.g., medical insurance paying a bill doesn’t count toward the plaintiff’s recovery)

Comparative negligence (tort law) – aka “non-absolute contributory negligence”, the fault/negligence of each party involved is based on the percentage responsibility for the event, a frequent concept in insurance

Concurrent delay doctrine (contract law) – when both parties of a contract cause delays, neither party can recover damages for the period of time when both parties were at fault

Contra proferentem – Latin for “against the offeror”, aka “interpretation against the draftsman”, when a promise, agreement or term is ambiguous the preferred meaning should be the one that works against the interests of the party who provided the wording

Contributory negligence (tort law) – the defense completely bars plaintiffs from any recovery if they contribute to their own injury through their own negligence

  • Last clear chance doctrine – in tort law when using contributory negligence, a negligent plaintiff can still recover if they can show the defendant had the “last clear chance” to avoid the accident

Corporate opportunity (trust law) – directors, officers, and controlling shareholders of a corporation must not take any business opportunity for themselves which could benefit their corporation

Crumbling skull rule (tort law) – when a plaintiff had a condition or injury that predates the tort and would have naturally deteriorated or worsened over time (e.g., a crumbling skull) the defendant is not responsible for that part of the condition or injury

Dumpor’s case rule (property law) – if a landlord consents to assigning a tenant’s interest in a lease, they implicitly consent to all future assignments by the assignee

Duty of care (tort law) – an individual must legally adhere to a set standard of practices to not risk harming others

Duty to rescue (tort law) – a party can be held liable for failing to come to the rescue of another party who could face potential injury or death without being rescued

Eggshell skull (tort law) – the unexpected frailty of the injured person is not a valid defense to the seriousness of any injury caused to them

Estoppel – if a person says something, they can’t use the law to redact their word

Ex turpi causa non oritur actio – Latin for “from a dishonorable cause an action does not arise”, aka “illegality defense”, a plaintiff cannot pursue legal action if they themselves performed something illegal in the event of that situation happening

Fireman’s rule (tort law) – aka “firefighter’s rule”, public safety officials like firefighters and police (and sometimes all public safety professionals) are not responsible for damages that occur in the course of their duties, even in cases of clear negligence by other parties

Four corners rule (contract/inheritance law) – If terms are ambiguous, the court must rely solely on the written instrument and can’t consider extraneous evidence

Fundamental breach – while most contract breaches nullify a contract in part, a breach can be so bad it nullifies a contract fully

Hotchpot rule – sometimes blending, combining or offsetting property (typically gifts) can ensure equality of a later division of property, most commonly in divorce proceedings

Intention to create legal relations (contract law) – aka “intention to be legally bound”, a court should presume parties to an agreement wish for that agreement to be legally binding, and it’s only legally enforceable if they intended it to be

Last shot rule (contract law) – a party will implicitly accept a counter-offer by indicating no objection to it, named after sellers normally “firing the last shot” by sending the final form in a negotiation

Laesio enormis (contract law) – a contracting party can rescind an agreement if the price of an exchange is less than 1/2 or 1/3 of its actual value

Locus standi – Latin for “standing location”, aka standing, where a party seeking a legal remedy must demonstrate that they are sufficiently connected to a law they’re claiming was violated

Mirror image rule – aka “unequivocal and absolute acceptance requirement”, an offer must be accepted exactly with no modifications, and an attempt to accept the offer on different terms instead creates a counter-offer

Parol evidence rule (contract law) – if a contract is written, then verbal agreements that had been made that weren’t captured in writing cannot be submitted as evidence

Posting rule (contract law) – a contract is typically bound at the date it was signed, but is only valid after the other party receives their expected goods

Pottery Barn rule (contract law) – if someone breaks an object on display for sale, they have created a contract to purchase it

Pre-existing duty rule (contract law) – performing a duty that existed before engaging in a contract doesn’t count as the duty that could form that contract

Privity of contract (contract law) – a contract can’t confer rights or impose obligations on anyone who isn’t a party to that contract

Proper law – the choice of law is a distinctive stage when there’s a conflict of applicable laws, and the state has regulations to determine which laws will apply

Res ipsa loquitur (tort law) – Latin for “the thing speaks for itself”, a court can infer negligence from the very nature of an accident or injury even when there’s no direct evidence of the defendant’s behavior

Restraints of trade (competition law) – unless the law has regulations directly overseeing a contract, everyone should have the freedom to regulate their own mode of making agreements according to their own discretion and choice

Rule in Dumpor’s Case – once a landlord consents to assigning a tenant to a lease, they implicitly consent to all future assignments by the that tenant

Subrogation – a third party (e.g., second creditor, insurance company) can assume another party’s legal right to collect a debt or damages

Substantial performance (contract law) – a court can imply a partial or substantially similar performance to stand in for a contract’s specified performance, an alternative principle to the perfect tender rule

Unconscionability – a contract that’s extremely one-sided is unethical to enforce


Assumption of risk (tort law) – a plaintiff’s right to recovery is reduced or barred against a negligent tortfeasor if the defendant can demonstrate the plaintiff voluntarily assumed the risks at issue inherent to their dangerous activity

Baseball rule – a baseball team isn’t responsible for injuries caused by a foul ball if they put protected seating for the most likely areas where a foul ball would travel

Calculus of negligence – aka “the Hand Rule”, the owner’s duty to provide against an injury is based on (1) the chances an injury might happen, (2) the severity of that injury, and (3) the burden was sufficient for taking precautions against risks

Faithless servant – in New York, employees who act unfaithfully toward their employers must give up all compensation they’ve received during that period of disloyalty

Learned intermediary – a manufacturer of a product has fulfilled its duty of care when it has provided all the necessary information to a “learned intermediary” who then interacts with the consumer of a product, primarily used by pharmaceutical and medical device manufacturers to defend tort suits

Rescue doctrine (tort law) – if the defendant creates a circumstance that places the victim in danger, they’re not only liable to the harm caused to the victim bu also harm caused to anyone injured while trying to rescue them

Substantial truth – a statement can’t be held as slander or libel if the statement is true but has “slight inaccuracies of expression”

Valid when made – if the terms of a loan are valid at their creation, they’re still valid if the lienholder is sold or assigned to another party


Common employment (tort law) – when workers injure their fellow workers, the company who employs them is not responsible

Indoor management rule (company law) – aka “Rule in Turquand’s Case”, people transacting with companies are entitled to assume internal company rules are honored, even when they’re not

Non-derogation from grants doctrine (property law) – a seller of realty or goods can’t take any action that will lessen the buyer’s value of the thing sold


Abstraction principle – the buyer and seller in a business contract don’t necessarily own the payment or the object after the transfer, and it requires 3 contracts:

  1. the contract of sale itself that obligates the seller to transfer ownership of the product to the buyer and the buyer to pay the price
  2. a contract that transfers ownership of the product to the buyer, fulfilling the seller’s obligation
  3. a contract that transfers ownership of the money from the buyer to the seller, fulfilling the buyer’s obligation

Other Legal Domains

Correlative rights doctrine (property law) – landowners’ rights to a common source of water (and oil and gas in some US states) is shared proportionally to the size of them and their neighbors’ land

Equivalents doctrine (patent law) – a court can hold a party liable for patent infringement when the infringing device doesn’t fall within the literal scope of a patent claim but is still equivalent to the claimed invention

Fair abridgment (copyright law) – aka “fair use” or “fair dealing”, a copyrighted work is free for use in specific situations like parody, non-commercial use, and education

Implied license (intellectual property law) – a licensee is allowed to do something that would normally require the express permission of the licensor if the licensor’s actions lead the licensee to believe they have permission

Inevitable disclosure (intellectual property law) – an employer can claim trade secret without needing proof or evidence to prevent a former employee from working a job that may result in using trade secrets

Internal affairs doctrine (corporations law) – aka “lex incorporationis”, the “internal affairs” of a corporation will be governed by the corporate statutes and case law of the state the corporation is incorporated

Last injurious exposure rule (employment law) – when an occupational disease was potentially caused by a succession of jobs, the most recent employer with the risk exposure is liable

nemo dat quod non habet (contract law) – Latin for “no one can give what they do not have”, the purchase of a possession from someone who doesn’t have it also denies the purchaser any title to ownership

Nondelegation principle – aka “nondelegation doctrine”, one branch of government must not authorize another entity to exercise the power or function it already has for itself

Open mines doctrine (property law) – depletion of nonrenewable natural resources is considered waste unless consuming those resources constitutes normal use of the land

Polluter pays principle (environmental law) – the party responsible for producing pollution must pay for the damage done to the natural environment

Rule in Shelley’s Case (trust law) – if a person gives an inheritance to their next of kin and the remainder to their grandchildren underneath that, the next of kin technically has all of it

Scène à faire (copyright law) – French for “scene that must be done”, when a scene in a created work is almost required for that genre, certain elements of it are not protected by copyright (e.g., homeless people in a poor part of a city)


Absolute priority (bankruptcy court) – aka “liquidation preference”, there’s an order to who gets paid in a bankruptcy: (1) debts to creditors (2) shareholders divide any remaining assets, with secured claims taking precedence over unsecured claims

Assignment of income doctrine (tax law) – each entity’s income must be their own for tax purposes

Boulevard rule (traffic court) – a driver of a vehicle entering a highway from a smaller road or entrance (“unfavored”) must stop and yield the right of way to all highway (“favored”) drivers

Cash equivalence doctrine (tax law) – certain non-cash payment transactions are treated

Economic substance (tax law) – a transaction must have a substantial purpose aside from reducing tax liability and an economic effect aside from the tax effect to qualify for any tax benefits

Essential facilities doctrine – a monopoly that owns a facility essential to its competitors must provide reasonable use of it

Exhausted combination doctrine (patent law) – aka “doctrine of the Lincoln Engineering case”, when an inventor invents a new, non-obvious device and tries to patent the new device and the combination of that new device with a known, conventional device it interacts with in a conventional way, that combination can’t be patented as well

Functionality doctrine (trademark law) – manufacturers can’t protect specific uses of a product with trademark law, since that’s a patent issue

First-sale doctrine (intellectual property law) – aka “exhaustion doctrine”, an intellectual property holder can control resale of products embodying its intellectual property, but the intellectual property is “exhausted” after a point

Foreign equivalents doctrine (trademark law) – courts and the TTAB must translate foreign words into English to determine if they can be registered as trademarks

Idea–expression distinction (copyright law) – the idea of a thing is different from the expression or manifestation of that idea

Illinois Brick doctrine (antitrust law) – indirect purchasers of goods and services along a supply chain cannot seek damages for antitrust violations committed by original manufacturer or service provider, though direct purchasers can

Inherency doctrine (patent law) – prior art may be relied on not only for what it expressly teaches, but for what flows from the express teachings, and a patent can be filed for a new and non-obvious symbolic representation

Market share liability (corporate law) – a plaintiff can establish an initial case against a group of product manufacturers for injury caused by a product, even when the plaintiff doesn’t know which defendant the product originated

Medical necessity (medical law) – a government is lawfully permitted to pay for activities deemed reasonable, necessary, or appropriate

Nominative use (trademark law) – aka “nominative fair use”, a person may use the trademark of another as a reference to describe the other product or compare it to their own

Perfect tender rule (contract law) – if the “perfect tender” of a good fails in any capacity, a buyer has the right to reject or accept all of the goods, or reject the nonconforming part, but can’t reject the goods outright in its entirety

Repair and reconstruction doctrine (patent law) – there is a difference between repairing (the right of an owner of property to preserve the function of a thing) and reconstruction (combining unpatented elements into a patented product)

Reverse doctrine of equivalents (patent law) – a device that appears to literally infringe a patent claim by having similar elements or limitations does not infringe it if it operates on a different principle

Rule of reason (antitrust law) – monopolies are only considered illegal when they’re unreasonably restraining trade

Step transaction doctrine (tax law) – formally separate steps are a single integrated event for tax purposes, designed to prevent tax abuse (e.g., tax shelters, bailing assets out of a corporation)

Sufficient similarity (EPA environmental law) – a chemical sample with an unknown toxicity must be treated with the same safety requirements as a similar chemical sample with a known toxicity

Tea Rose – Rectanus doctrine (trademark law) – the junior user of a trademark who is geographically remote from the senior user can have priority in their geographical area


Maxwellisation (trade law) – people who are to be criticized in an official report must be given advance notice and able to respond to the details of that criticism


Spider in the web doctrine (patent law) – the Dutch courts only assume jurisdiction where the main defendant (the “spider”) is located in the Netherlands and the other defendants were part of a group of companies and acted on a common business policy of the group (the “web”)

Large-Scale Multi-Entity Doctrines

Constitutionality presumption – the judiciary should presume the legislature’s statutes are constitutional

Enrolled bill rule – once a bill passes a legislative body and is passed into law, the courts assume all rules of procedure in the enactment process were properly followed

Exhaustion of remedies – a litigant can’t seek a remedy in a new court or jurisdiction until all claims or remedies in that court have been fully exhausted

Forum non conveniens – Latin for “an inconvenient forum”) – a court acknowledges another forum or court is a more appropriate one, so they transfer the case to that forum

Implied repeal – when a legislative act conflicts with a previous one, the later act takes precedence and the conflicting parts of the earlier act become legally inoperable

Inherent powers – a state has certain non-negotiable powers

Judicial deference – aka “Chevron deference”, a court will yield or submit its judgment to another legitimate party (e.g., the executive branch in the interests of national defense)

Judicial discretion – judicial powers can make some legal decisions according to their discretion without precedent, legislation, or a constitution

Jus sanguinis – Latin for “blood right”, a person has the right to become the nationality/citizenship of their heritage, contrast to jus soli

Jus soli – Latin for “soil right”, aka “birthright citizenship”, a person has the right to become the nationality/citizenship of the country they’re born in, contrast to jus sanguinis

Law of the case – if an appellate court doesn’t take a lower court’s case, it won’t do it again later with the same substantial facts

Legal transplant – the best way to test out new governments is for laws to transplant and adapt into new government and court systems

Margin of appreciations (human rights law) – in the European Convention of Human Rights, courts can reconcile practical differences in reconciling articles of the convention pertaining to human rights

Mozambique rule – a court has no jurisdiction over foreign land disputes

Necessity doctrine – an administrative authority can lawfully take extraordinary actions that contravene established constitution, laws, norms, or conventions if it restores order or upholds fundamental constitutional principles

Non-refoulement – a nation cannot send a refugee to a country if they’re at risk of persecution there

Odious debt – aka “illegitimate debt”, the national debt incurred by a despotic regime should not be enforceable

Peremptory norm – aka “jus cogens”, some cultural norms are not permitted to ever be lawful (e.g., genocide, slavery, maritime piracy)

Public trust doctrine (environmental law) – the sovereign holds some resources in trust for public use, regardless of private property ownership (e.g., shoreline between high and low tides

Rule against foreign revenue enforcement – aka “revenue rule”, one country will not enforce another country’s tax laws

Separation of powers doctrine – To keep the roles separate to avoid tyranny, a constitutional government requires 3 different branches (Legislative, Executive, and Judicial) with defined abilities that can check the power of the others

Stopping the clock (USA & Canada) – sometimes, to meet a Constitutional deadline, a legislature will sometimes literally stop the clock or push out a deadline to meet requirements for procedure

Subsidiarity – social and political issues should be dealt with at the most immediate or local level that’s consistent with the resolution

Substance over form – the essence of something (its “substance”) is more relevant than its structure (its “form”)

Territorial principle – aka “territoriality principle”, each sovereign state can exercise its own exclusive jurisdiction over individuals and entities within its territory, including prosecuting for criminal offenses and arresting/apprehending individuals

Tipsy coachman doctrine – a ruling in a higher court that rules the same way will still stand even when the lower court used the wrong reasoning to get to the same conclusion

Universal jurisdiction – governments and international organizations can claim criminal jurisdiction over an accused person regardless of the situation (e.g., where the crime was committed, that person’s nationality, affiliations)


Abstention doctrine – one of several doctrines a US court can apply to refuse hearing a case if it interferes with another court’s powers

Act-of-state doctrine – Every sovereign state is bound to respect the independence of every other sovereign state, so courts won’t judge the acts of other governments or foreign sovereign nationals

Adequate and independent state ground – A federal Supreme Court decision doesn’t have jurisdiction over a case if the state ground is (1) “adequate” to support the judgment and (2) “independent” of federal law

Alford doctrine/plea – a defendant can not admit to the criminal act and will assert their innocence, but can admit the evidence presented would create a guilty verdict beyond a reasonable doubt if placed in front of a judge/jury, the basis of most plea bargains

Equal footing doctrine – all states brought into the United States have the exact same status as the existing states

Erie doctrine – for federal courts managing non-federal questions, they must apply state-based answers

Executive privilege – the president of the USA and other executive branch members can maintain confidential communications under certain circumstances within the executive branch, and can resist some some legal actions by the legislative and judicial branches

Implied powers – some powers are not directly stated in the Constitution, but are implied to be available based on previously stated power

Ker–Frisbie doctrine – criminal defendants may be prosecuted in US courts irrespective of whether an extradition treaty was used

Major questions doctrine – aka “major rules doctrine”, if an agency seeks to decide on an issue of major national significance its action must be supported by clear statutory authorization

Mount Laurel doctrine – in New Jersey, municipalities must use their zoning powers to provide a realistic opportunity for producing affordable housing to low- and moderate-income households

Parker immunity doctrine (antitrust law) – government authorities are immune to liability when they create regulations with anticompetitive effects

Political question doctrine – a constitutional dispute that’s not a legal discussion, uses techniques not related to court procedures, or is explicitly assigned to Congress or the President is considered political and is outside the scope of the courts, refers to separation of powers doctrine

Purcell principle – courts should not change election rules too closely to an election because it may cause confusion

Rooker-Feldman doctrine – Federal courts that aren’t the Supreme Court can’t make decisions for appeals that arose from state courts, which means that any state appeal goes all the way up to the Supreme Court

State action doctrine – While a state is required to honor equal protections against individuals, individuals don’t have to honor equal protections against other individuals, points to 14th Amendment


Demise of the Crown – when a monarch dies or abdicates their throne, the Crown and its authority automatically transfers to that monarch’s heir

Inherent jurisdiction – a superior court has the jurisdiction to hear any matter that comes before it unless a law prohibits it


Double aspect doctrine – laws can be created by both provincial and federal governments in relation to the same subject matter

Living tree doctrine – a constitution is organic and must be read in a broad and progressive manner to adapt to changing times

Pith and substance – the essential character of the law (“pith and substance”) must can be assigned to the appropriate provincial or federal government depending on which part of the Constitution it falls under


Basic structure doctrine – the constitution of a sovereign state has certain characteristics that can’t be erased by its legislature

Colourability doctrine – when a legislature wants to do something its constitution forbids, it “colours” the law with a substitute purpose that permits that legislature to accomplish its original goal


Exceptional circumstances – a government agency or government leader can receive additional powers to alleviate or mitigate unforeseen or unconventional hardship


Conferral principle – all EU competences are voluntarily conferred on it by its member states, so the member states’ influence supersedes all EU precepts

Largely Obsolete

Charitable immunity – a charitable organization is not liable under tort law (nullified in mid-20th century)

Discovery doctrine – a European nation which discovers previously unknown territory to Europeans gives the discovering nation title to that territory against all other European nations, which can be perfected by possession (everything has been discovered now)

Indivisibility doctrine – in copyright law, only an owner can assign a copyright, and an asignee to those rights was a “mere licensee” who couldn’t assign further rights (eliminated in Copyright Act of 1976, and asignees can now file suit against infringers)

Jacitation (UK and Irish law) – aka “jacitation of marriage”, when a person falsely states they’re married to someone else, that person can put a restraining order on them to not say it again (abolished by 1996)

Fairness doctrine (USA’s FCC communications law) – the holders of broadcast license must provide both sides of a controversial issue of public importance that fairly reflects both viewpoints (removed from federal register in 2011)

Gravi de pugna – God will make the morally superior side win in a war (Catholic influence is no longer prevalent in most jurisprudence)

Stadtluft macht frei – German for “urban air makes you free”, in the 11th century a serf could not be reclaimed by his employer after a year and a day, and was therefore bound to the city and in some ways outside the feudal system