Casus Omissus

Casus omissus is a legal principle indicating that a specific situation or case has been intentionally omitted from a statute or legal provision. As such, it suggests that the courts should not fill in the gaps by judicial interpretation but should apply the law as it stands, without extending its provisions to cases that the legislature did not intend to cover.

The principle 'casus omissus' has roots in Roman law, where it was recognized that statutes should be interpreted according to their plain meaning without judicial extension. It reflects a respect for legislative intent and clarity in statutory drafting.

In modern law, casus omissus is applied to maintain the integrity of statutory interpretation, preventing courts from interpolating or extending laws to situations not expressly included by the legislature. Courts often invoke this principle to ensure that legislative gaps are not filled through judicial activism, thereby preserving the separation of powers.

• A statute that provides penalties for certain environmental violations but does not mention others will only apply to those specified violations according to the casus omissus principle.
• When interpreting tax laws, if a statute defines a specific deduction without mentioning similar expenses, the courts will not allow those other expenses to be deducted based on the omission.

• United States v. Smith, 508 U.S. 223 (1993)