A Dozen Canons of Statutory and Constitutional Text Construction

1. Supremacy-of-Text Principle. The words of a governing text are of paramount concern, and what they convey, in their context, is what the text means.
2. Principle of Interrelating Canons. No canon of interpretation is absolute. Each may be overcome by the strength of differing principles that point in other directions.
3. Presumption of Validity. An interpretation that validates outweighs one that invalidates (ut res magis valeat quam pereat).
4. Ordinary-Meaning Canon. Words are to be understood in their ordinary, everyday meanings — unless the context indicates that they bear a technical sense.
5. Fixed-Meaning Canon. Words must be given the meaning they had when the text was adopted.
6. Omitted-Case Canon. Nothing is to be added to what the text states or reasonably implies (casus omissus pro omisso habendus est). That is, a matter not covered is to be treated as not covered.
7. General-Terms Canon. General terms are to be given their general meaning (generalia verba sunt generaliter intelligenda).
8. Negative-Implication Canon. The expression of one thing implies the exclusion of others (expressio unius est exclusio alterius).
9. Whole-Text Canon. The text must be construed as a whole.
10. Presumption of Consistent Usage. A word or phrase is presumed to bear the same meaning throughout a text; a material variation in terms suggests a variation in meaning.
11. Surplusage Canon. If possible, every word and every provision is to be given effect (verba cum effectu sunt accipienda). None should be ignored. None should needlessly be given an interpretation that causes it to duplicate another provision or to have no consequence.
12. Absurdity Doctrine. A provision may be either disregarded or judicially corrected as an error (when the correction is textually simple) if failing to do so would result in a disposition that no reasonable person could approve.

— U.S. Supreme Court Justice Antonin Scalia & Bryan A. Garner are co-authors of Reading Law: The Interpretation of Legal Texts (West, 2012).Available on Amazon at http://www.amazon.com/Reading-Law-Interpretation-Legal-Texts/dp/031427555X