A heinous crime is an action that is not just illegal, but it is also considered hateful or reprehensible. Governments sometimes judge whether crimes such as murder are heinous to assess penalties. The death penalty, for instance, is a capital punishment used in some municipalities to condemn heinous crimes.
Though this phrase is sometimes used in court cases, whether a crime is heinous or not is often subjective. Many people feel that murders of children or killings that are especially brutal are heinous. People who have suffered family loss at the hands of a drunk driver may view drunk driving as more heinous than those who haven't.