Expressio Unius

Expressio Unius is a legal doctrine that posits that the inclusion of one or more specific items in a list implies the exclusion of others not listed. This principle is often employed in statutory interpretation to clarify legislative intent.

The principle has roots in Roman law and has been traditionally applied within common law jurisdictions to derive meaning from statutes. Its usage has evolved over centuries as courts sought clarity in ambiguous legislative language.

In modern law, Expressio Unius is frequently used by courts when interpreting statutes or contracts that enumerate specific classes of items or rights. It supports the notion that legislators' intentionality can be discerned from what they explicitly include or exclude in their written provisions.

• If a statute specifies that 'only vehicles not exceeding 10,000 pounds' may use a toll road, other vehicles such as buses or trucks above that weight limit are implicitly excluded from using the road.
• In a contract that states, 'The tenant shall maintain the garden and the porch,' it can be inferred that the tenant is not required to maintain any other part of the property not mentioned.

• Bishop v. Bishop, 1818
• Friedman v. New York City Transit Authority, 1999