expressio unius est exclusio alterius

When a statute expressly names some things, the court may infer that the legislature meant to exclude others of the same kind that are not named. If an Act gives a right of appeal against certain orders, the inference is that other orders are not appealable; if a provision lists persons entitled to a benefit, others are excluded.

The maxim is a guide, not a rule, and courts call it a “valuable servant but a dangerous master”. It yields where the omission is accidental, where the listed items are only examples, or where its application would lead to an absurd or unjust result, or go against the clear object of the statute. It is often contrasted with ejusdem generis.

Example

Since s.104 lists the orders that are appealable, expressio unius est exclusio alterius suggests that no appeal lies from orders it omits.

See also

ejusdem generis · external aids to interpretation

Read more in the study notes

• Secondary rules: noscitur a sociis, ejusdem generis, reddendo singula singulis, expressio unius (Interpretation of Statutes and Principles of Legislation)