Fall 2025 Criminal Law I

Mens Rea

Culpable mental state.

Actus Reus

Prohibited willed bodily movement or culpable omission.

In re Winship (U.S. 1970)

Criminal elements must be proved “beyond a reasonable doubt.”

Presumption of Insuperfluity

Words in a statute have meaning. No such thing as a wasted word.

Presumption of Consistent Usage

Words in a statute have consistent meaning, unless otherwise stated.

Ejusdem Generis

A statute affecting a class of items also affects similar items that are unlisted.

Expressio unius est exclusio alterius

Expressing one thing means excluding another.

Rule of Lenity

Ambiguities that are not reasonably settled are interpreted in the defendant’s favor.

Limitations on Power to Criminalize

1. Ex post facto

2. Bills of Attainder

3. Vagueness

4. Eight Amendment

5. Status