Canons Simplified w/ Examples

Question 1

Artificial-Person Canon

Answer 1

Definition: “Person” usually includes companies, but not governments.
Example: If a law fines a “person” for pollution, a business can be fined, but not the federal government.

Question 2

Casus Omissus

Answer 2

Definition: If something was left out of a law, assume it was intentional.
Example: If a law gives discounts to “students and seniors,” but not veterans, courts won’t add veterans.

Question 3

Conjunctive/Disjunctive Canon

Answer 3

Definition: “And” means all items apply; “or” means any one of them.
Example: “Applies to theft and fraud” means both must be proven. “Theft or fraud” means just one.

Question 4

Ejusdem Generis

Answer 4

Definition: A general word after specific items should be similar to those items.
Example: “Cats, dogs, and other animals” likely doesn’t include sharks—just similar domestic animals.

Question 5

Expressio Unius

Answer 5

Definition: If a law lists some things, other things not listed are excluded.
Example: If a law protects “cars, trucks, and motorcycles,” it doesn’t protect bicycles.

Question 6

Gender/Number Canon

Answer 6

Definition: Singular words can include plural (and vice versa), and masculine includes feminine.
Example: “He shall report” can include “she shall report.”

Question 7

General/Specific Canon

Answer 7

Definition: A specific law overrides a general one when they conflict.
Example: A law about taxes on books would trump a general law about business taxes.

Question 8

General-Terms Canon

Answer 8

Definition: General words are to be understood broadly.
Example: “Any vehicle” could include cars, trucks, scooters, etc., unless limited elsewhere.

Question 9

Grammar Canon

Answer 9

Definition: Statutes follow standard grammar rules.
Example: Verb tense can show timing of legal duties—past, present, or future.

Question 10

Harmonious-Reading Canon

Answer 10

Definition: Interpret the law so all parts work together, not against each other.
Example: Don’t read one section in a way that contradicts another.

Question 11

Irreconcilability Canon

Answer 11

Definition: If two parts of a law can’t both work, neither may apply.
Example: If one part says “open 24/7” and another says “close on Sundays,” they may cancel each other out.

Question 12

Legislative History Canons

Answer 12

Definition: Courts may look at what lawmakers said when passing a law, if the law is unclear.
Example: A judge checks committee reports to clarify a confusing term in the statute.

Question 13

Mandatory/Permissive Canon

Answer 13

Definition: “Shall” usually means required; “may” usually means optional.
Example: “The agency shall act” = must act. “The agency may act” = can choose to act.

Question 14

Nearest-Reasonable-Referent Canon

Answer 14

Definition: Modifiers usually apply to the closest noun.
Example: “Applies to owners of cats, dogs, and birds with collars” = only birds need collars.

Question 15

Noscitur a Sociis

Answer 15

Definition: Words gain meaning from surrounding words.
Example: In “whiskey, rum, and other beverages,” “beverages” likely refers to alcohol.

Question 16

Ordinary Meaning Canon

Answer 16

Definition: Use the everyday meaning of words unless the law defines them otherwise.
Example: “Vehicle” means car or truck, not spaceship—unless the law says otherwise.

Question 17

Plain Meaning & Absurdity Doctrine

Answer 17

Definition: Use the obvious meaning—unless it leads to a ridiculous result.
Example: If a law says “no vehicles in the park,” that doesn’t mean banning ambulances in emergencies.

Question 18

Predicate-Act Canon

Answer 18

Definition: If an act is allowed, the necessary steps to perform it are also allowed.
Example: If a law lets you build a house, it also allows buying land and materials.

Question 19

Prefatory-Materials/Headings Canon

Answer 19

Definition: Titles, headings, and preambles can help explain meaning but aren’t controlling.
Example: A section title like “Tax Relief” can suggest intent but doesn’t override the law’s words.

Question 20

Presumption of Consistent Usage

Answer 20

Definition: The same word in the same law usually has the same meaning.
Example: If “employee” is defined one way in one part, it means the same in other parts.

Question 21

Presumption of Nonexclusive ‘Include’

Answer 21

Definition: “Including” means examples, not a complete list.
Example: “Vehicles including cars and trucks” also covers motorcycles.

Question 22

Presumption of Validity

Answer 22

Definition: Interpret the law in a way that makes it work.
Example: Don’t read the law in a way that makes it unenforceable or contradictory.

Question 23

Proviso Canon

Answer 23

Definition: A “provided that” clause usually limits only the sentence right before it.
Example: “All fees are due—provided that students get an extension” applies only to students.

Question 24

Punctuation Canon

Answer 24

Definition: Punctuation matters when interpreting meaning.
Example: “Eats, shoots and leaves” means something different with or without a comma.

Question 25

Purposive Construction

Answer 25

Definition: Read the law to serve its overall purpose. Example: A health care law should be read to help patients, not block treatment.

Question 26

Reddendo Singula Singulis

Answer 26

Definition: Match each part of a sentence to the part it relates to. Example: “He gave roses and she lilies to their mothers and sisters” = roses to mother, lilies to sister.

Question 27

Rule Against Surplusage

Answer 27

Definition: Every word should have a purpose—nothing is extra. Example: Don’t interpret two words as meaning the same thing, or one becomes useless.

Question 28

Rule of the Last Antecedent

Answer 28

Definition: A phrase usually refers only to the word just before it. Example: “Applies to dogs with long tails” = only long-tailed dogs, not all dogs.

Question 29

Scope-of-Subparts Canon

Answer 29

Definition: Indented items belong to the section above them. Example: Bulleted rules under a heading apply only to that section.

Question 30

Series-Qualifier Canon

Answer 30

Definition: A final modifier can apply to an entire list if the grammar supports it. Example: “Applies to dangerous dogs, cats, and birds kept as pets” = “kept as pets” applies to all.

Question 31

Subordinating/Superordinating Canon

Answer 31

Definition: Phrases like “subject to” or “notwithstanding” decide which part wins in a conflict. Example: “Subject to local laws” = local laws override federal rule here.

Question 32

Unintelligibility Canon

Answer 32

Definition: If a law is truly impossible to understand, it’s void. Example: A law with no clear rules may not be enforceable.

Question 33

Whole-Text Canon

Answer 33

Definition: Read the entire law together, not one part in isolation. Example: A confusing clause might make sense when read with the rest of the statute.

Question 34

Canon of Constitutional Avoidance

Answer 34

Definition: If one reading of a law would raise serious constitutional issues, pick another (reasonable) one. Example: If one interpretation would violate free speech, pick the other meaning that doesn’t.

Question 35

Dog That Didn’t Bark Presumption

Answer 35

Definition: If Congress doesn’t mention changing a law, assume it didn’t mean to change it. Example: If an old rule isn’t discussed during a new law’s passage, courts assume the rule still applies.

Question 36

Federalism Canons

Answer 36

Definition: Courts assume Congress doesn't mess with state power unless it says so clearly. Example: A vague law won’t be read to let the federal government take over state decisions.

Question 37

In Pari Materia

Answer 37

Definition: Related laws should be read together as one. Example: A tax law and a refund law that cover the same topic should be interpreted consistently.

Question 38

Mens Rea Canon

Answer 38

Definition: Crimes usually require a guilty mind (intent), unless Congress clearly says otherwise. Example: If a law just says “it’s illegal to dump waste,” courts usually assume it means knowingly dumping waste.

Question 39

Nondelegation Doctrine

Answer 39

Definition: Congress must give clear limits if it delegates power to agencies. Example: Congress can’t just say “the agency can do what it wants” with no guidelines.

Question 40

Penalty/Illegality Canon

Answer 40

Definition: If a law penalizes something, it’s also making it illegal. Example: A $500 fine for doing something means that thing is unlawful, not just discouraged.

Question 41

Pending-Action Canon

Answer 41

Definition: New laws apply to ongoing cases unless it would be unfair or retroactive. Example: If a law changes court rules during a case, the court usually applies the new version—unless it’d harm fairness.

Question 42

Presumption Against Extraterritoriality

Answer 42

Definition: U.S. laws don’t apply outside the U.S. unless Congress clearly says so. Example: A law about pollution in the U.S. doesn’t apply to factories in another country unless clearly stated.

Question 43

Presumption Against Hiding Elephants in Mouseholes

Answer 43

Definition: Big changes in law don’t come from small or vague parts of a statute. Example: Congress wouldn’t overhaul healthcare through a footnote in a food law.

Question 44

Presumption Against Implied Repeals

Answer 44

Definition: Laws don’t get canceled just because a new law conflicts—Congress must be clear. Example: If two laws say different things, courts try to make them work together unless one clearly overrides the other.

Question 45

Presumption Against Implied Right of Action

Answer 45

Definition: If a law doesn’t say people can sue, courts assume they can’t unless it's really obvious. Example: If a law says “employees must get breaks” but doesn’t say “they can sue,” courts don’t assume the right to sue.

Question 46

Presumption Against Retroactive Legislation

Answer 46

Definition: Laws apply going forward, not backward—unless Congress clearly says otherwise. Example: A 2025 tax law won’t apply to income from 2023 unless explicitly written that way.

Question 47

Presumption Against Waiver of Sovereign Immunity

Answer 47

Definition: The government can’t be sued unless it clearly says it can be. Example: If the law doesn’t clearly allow lawsuits against the U.S., they’re usually blocked.

Question 48

Presumption for Retaining the Common Law

Answer 48

Definition: If a law touches an area of traditional (common) law, courts assume it sticks to those rules unless it clearly changes them. Example: If a contract law uses the word “fraud,” it carries the same meaning courts have used for centuries.

Question 49

Presumptions in Favor of Judicial Process

Answer 49

Definition: Courts assume people still have access to the courts unless Congress clearly says otherwise. Example: Congress must speak clearly to stop people from suing or from having a jury trial.

Question 50

Presumption of Continuity

Answer 50

Definition: If Congress rewrites a law, assume it wanted to keep things the same unless it clearly changed something. Example: Replacing “permit” with “license” doesn’t mean the rules change unless explained.

Question 51

Presumption of Legislative Acquiescence

Answer 51

Definition: If Congress doesn’t change a law that courts or agencies interpret a certain way, assume Congress agrees. Example: If courts interpret a law one way for 30 years and Congress doesn’t change it, courts assume Congress is fine with that meaning.

Question 52

Presumption of Narrow Construction of Exceptions

Answer 52

Definition: Exceptions to rules are read narrowly so they don’t swallow the rule. Example: If a law bans guns but allows “lawful exceptions,” courts interpret “lawful exceptions” strictly.

Question 53

Presumption of Purposive Amendment

Answer 53

Definition: If Congress amends a law, it must’ve meant to change something important. Example: If “taxes” becomes “income taxes,” that change has meaning.

Question 54

Repeal-of-Repealer Canon

Answer 54

Definition: If Congress repeals a repeal, the original law doesn’t come back automatically. Example: If Law A is repealed by Law B, and Law B is later repealed, Law A doesn’t magically come back.

Question 55

Repealability Canon

Answer 55

Definition: No Congress can make a law that future Congresses can’t change. Example: Even if Congress says a law is “forever,” a future Congress can repeal it.

Question 56

Rule of Lenity

Answer 56

Definition: If a criminal law is unclear, interpret it in favor of the defendant. Example: If it’s not clear whether an action is criminal, the benefit of the doubt goes to the accused.