M’Naghten Rule

A 1843 ruling by the House of Lords, also largely valid in the US, which holds that a person accused of a crime is not criminally liable thereof if he/she ’...was labouring under such a defect of reason from disease of the mind as not to know the nature and quality of the acts, or, if he did know it, that he did not know that what he was doing was wrong’
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.