This book provides a leading point of reference in the field of partial defences to murder and with respect to the mental condition defences of loss of control and diminished responsibility in general. The work includes contributions from leading specialists from different jurisdictions. Divided into two parts, the first provides an analysis from the perspective of the UK, looking at particular concerns such as domestic violence, revenge and mixed motive killings, mistaken beliefs. The second part presents a comparative and international view to provide a wider background of how alternative systems treat issues of human frailty short of full insanity (loss of control, diminished responsibility) in the context of the criminal law.