Judges of every school use canons of construction: rules of thumb about how language usually works. The textual canons refine the search for ordinary meaning. Several have Latin names, and you will see them in opinions.
| Canon | Meaning | Example |
|---|---|---|
| Expressio unius est exclusio alterius | listing some things implies the exclusion of others | "Dogs, cats and rabbits may be kept" suggests ferrets may not |
| Ejusdem generis ("of the same kind") | general words after a list of specific ones take the list's kind | "cars, trucks, motorcycles and other vehicles": vehicles like those, not airplanes |
| Noscitur a sociis ("known by its companions") | an unclear word takes meaning from its neighbors | in "tacks, nails and staples," "staples" means fasteners, not basic foods |
| Rule against surplusage | read every word to do some work; avoid readings that make words pointless | if "sell" already covers "give," why did the law say "sell or give"? |
| Whole-act rule; consistent usage | read a provision with the whole statute; the same word usually means the same thing throughout | "employee" in section 2 and section 9 means the same |
Key idea
Textual canons are rules of thumb about language: expressio unius, ejusdem generis, noscitur a sociis, the rule against surplusage and the whole-act rule. They are presumptions, not commands: context can overcome them.
Why it works
The canons describe how careful writers and readers usually use words. If a drafter wanted to reach everything, why list specifics? If two words meant the same thing, why use both? Applying a canon is a way of asking what an ordinary, attentive reader would take the words to mean. But canons can point in different directions. In a famous 1950 article Karl Llewellyn paired canons that seemed to contradict each other ("thrust" and "parry"). Defenders reply that canons are tools for weighing evidence of meaning, not formulas.
Worked example: Is a fish a "tangible object"?
A federal law punishes anyone who destroys "any record, document, or tangible object" to obstruct a federal investigation. A fisherman threw undersized fish overboard. In Yates v. United States (2015), did the law reach the fish?
- A fish is a tangible object in ordinary speech.
- But four justices (the plurality) applied noscitur a sociis and ejusdem generis: "tangible object" sits beside "record" and "document," so it means objects used to record or preserve information. Justice Alito agreed with the result on similar grounds.
- Four justices dissented, reading "tangible object" in its ordinary, broad sense.
Answer: No, 5–4: the fish were not "tangible objects" under that provision.
Worked example: Apply ejusdem generis
A park rule bans "skateboards, roller skates, scooters and other wheeled devices." Does it ban a child's wagon? A wheelchair?
- The list names things people ride for recreation or travel on small wheels.
- "Other wheeled devices" takes that kind: ridden recreation devices.
- A wheelchair is a mobility aid, a different kind; a wagon is pulled, not ridden, so it is a closer question.
Answer: The wheelchair is likely outside the rule; the wagon is arguable.
Common mistake
Applying ejusdem generis to any list. It applies when general words follow specific ones ("cars, trucks and other vehicles") and limits the general words to that kind. A list with no catch-all at the end calls for expressio unius or noscitur a sociis instead. Check: is there a general catch-all phrase after the list?
This is an educational course, not legal advice.