Summary

The United States system of justice functions based on established legal regulations that are codified via the criminal law, all of which have deep historical roots. These statutes are found at both the state and federal level and should be written in such a way as the lay person on the street would not have a problem understanding their meaning (substantive law).  That is not the end of it, however, because the written law has to be interpreted by the triers of fact (judges) and the collective decisions from the courts form the basis of the case law.  Further, before government can take a person’s liberty, property, or life, it must ensure that due process is followed (procedural law).  In the adversarial system of justice, the government must prove that an act actually occurred (actus reus) and that the alleged offender intended to commit the act (mens rea).  There are several possible defenses against a criminal charge and the defendant works closely, at least in most cases, to determine the best option for him/her.

There continues to be a debate as to which behaviors should and should not be criminalized, although there is agreement that the more egregious acts of murder, assault, rape, arson, burglary, robbery, etc. should be legislated against.  These debates will continue into the future with some behaviors perhaps being decriminalized (e.g. drug use) while others may be added, by law, to the list of already-existing statutes.