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In a criminal offence for which more than one person is liable, the principal (strictly, 'principal offender') is the one held to have been the most direct cause of the Actus Reus (see: Accomplice). This is usually the person who carried out the act, or contributed most directly to it. However, in cases where the act was carried out by an innocent agent (e.g., a child under the age of criminal responsibility) then the principal will be deemed to be the person with the greatest role in the assistance of the offence.