Unlike civil law, which is concerned with the rights and relationships of individuals, criminal law is concerned with crimes against society. Most such crimes are punished by imprisonment but in a few cases, the punishment can be death. A capital crime is usually considered a crime that involves death or is punishable by death. The killing of a police officer is an example of a capital crime. There are however exceptions to this. Not all capital crimes are punished by death. For example, in some states, sex offenses involving children are called capital crimes. And while these crimes may not be punishable by death, they are punishable by a mandatory prison sentence. For more information on capital crimes, consult an attorney who is knowledgeable in the area of criminal law.