Unlawful homicide that does not amount to the crime of murder. There are two main categories: voluntary manslaughter and involuntary manslaughter. Voluntary manslaughter arises when a defendant is charged with murder but successfully pleads a partial defence of provocation (Homicide Act 1957 s 3), diminished responsibility (s 2), or suicide pact (s 4). Involuntary manslaughter consists of unlawful killing of another person with a * mens rea not amounting to intention. Although the distinctions between forms of involuntary manslaughter remain unclear in law, it is generally understood to consist of subjective recklessness manslaughter (R v Pike  Crim LR 547), constructive manslaughter (also called unlawful act manslaughter: R v Arobieke  Crim LR 314), gross negligence manslaughter (R v Adomako  1 AC 171), and corporate manslaughter (Corporate Manslaughter and Corporate Homicide Act 2007). The maximum penalty for manslaughter is life imprisonment. See also gross negligence.