In the English law of homicide, manslaughter is a less serious offence than murder, the differential being between levels of fault based on the mens rea (Latin for "guilty mind"). In England and Wales, the usual practice is to prefer a charge of murder, with the judge or defence able to introduce manslaughter as an option (see lesser included offence). The jury then decides whether the defendant is guilty or not guilty of either murder or manslaughter. On conviction for manslaughter, sentencing is at the judge's discretion, whereas a sentence of life imprisonment is mandatory on conviction for murder. Manslaughter may be either voluntary or involuntary, depending on whether the accused has the required mens rea for murder.