Actus reus I: Focus on Conduct and Omission

The structure of a criminal offence – Actus reus I: Focus on conduct and omission


The Elements of a Crime


  • Actus Reus


Actus reus refers to the act or omission that contain the physical elements of a crime and is known as a ‘guilty act’. 



  • Mens Rea

Mens rea refers to the intention or knowledge of wrongdoing that is part of a crime and is known as the ‘guilty mind’ or ‘internal element’.


What is required for a successful criminal conviction?


Actus reus + mens rea – any defences = criminal conviction


Actus Reus: The External Elements of the Offence


  • Conduct or omission:

The defendant’s (D) physical acts or omissions required for liability. The external movement of D’s body.


  • Circumstance:

Facts surrounding D’s conduct requires liability. Some crimes require a specific circumstance to exist. For example, for theft there must be property belonging to another and for sexual offences there must be intercourse without consent.


  • Result:

The effects of D’s acts required for liability. For some crimes, the conduct must cause a specific result. For example, for assault occasioning actual bodily harm and for murder there must be a dead person.


  • Causation:

This is the relationship between the conduct (or omission) and the result. (Please see the Causation topic for detailed information).



Omission Liability


There is a reluctance to impose liability for omission to act. However, there can be liability where there is


  • A recognised offence
  • A duty to act
  • A breach of that duty.


Key cases:


Winzar v Chief Constable of Kent (1983) 1 WLUK 670


Gibbins & Proctor (1918) 4 WLUK 25


DPP v Santana Bermudez [2003] EWHC 2908 (Admin)


R v Miller [1983] 2 AC 161


R v Dytham [1979] 3 WLR 467


Instan [1893] 1 QB 450


R v Evans [2009] 2 Cr APP R 10


Stone and Dobinson [1977] 1 QB 354