Criminal law deals with crimes and their punishment. Based on their nature, crimes are generally categorized as felonies or misdemeanors . A felony is a serious misconduct punishable by death or by imprisonment for more than one year; whereas a misdemeanor is a misconduct for which the law prescribes punishment of no more than one year in prison. Sometimes crimes are also categorized as mala in se and mala prohibita . Mala in se comprises those acts that are thought to be immoral or wrong in themselves, or naturally evil, such as murder, rape, arson, burglary, and the like; whereas mala prohibita are acts that are not naturally evil but are prohibited by the statute because they infringe on the rights of others. For an act to be constituted a crime, the statute states that it must also be accompanied by criminal intent, or a negligence that may be regarded by law as equivalent to criminal intent.

A lawyer who specializes in criminal law is called a criminal lawyer. In Hawaii, some of the areas covered by a criminal lawyer include: