University Taster
Law – University Taster
4.1 Actus Reus and Mens Rea
In criminal law, two key ideas are used to determine if someone is guilty of a crime - actus reus and mens rea. Actus reus refers to the physical act of the crime while mens rea is about the person’s state of mind or intention. Both are needed to prove that a crime has been committed under the common law system in the UK.
Actus Reus
Actus reus refers to the physical element of a crime. It’s what the person accused of the crime must be shown to have done, or failed to do. It can consist of:
- An act: A deliberate action, such as striking someone in an assault.
- An omission: A failure to act when there is a legal duty to do so.
- A state of affairs: Situations where liability arises simply because of a particular set of circumstances.

Continue the lesson
This section is available to learners with course access. Continue learning with Knowness to unlock the full explanation, examples, revision tools, and progress tracking.
The remaining lesson content includes further guided explanation, important learning points, and supporting interactive material designed to help you understand and revise this topic.
Unlock this topic to view the full activity, worked examples, common mistakes, and additional revision support.
More content available
Knowness lessons are structured to build understanding step by step. Create an account or upgrade your access to continue from this point.
This preview does not include the hidden lesson text, answers, explanations, or embedded interactions.
Continue learning with Knowness
Sign up to access the full lesson, predicted grades, revision tools, progress tracking, and more.
Create a free account