In many systems of law, criminal guilt requires not only that an act was performed (actus reus) but also that it was performed with an appropriate mind-set. Having the intention to perform a crime is sufficient, but not necessary to mens rea. Foreseeing a side-effect such as a death could count, even if the death is not intended, and reckless negligence could also constitute mens rea. In wider contexts than law the phenomenon of moral luck means that people may acquire a burden of guilt or shame without having intentionally done any wrong or having negligently failed to do what they ought to have done. See also piacular.