Justice systems generally are divided into two main areas: civil and criminal. Civil law encompasses all disputes between two or more private parties. These may include individuals, corporations, or government agencies. Criminal law is generally defined as crimes against the state, understood as violations of the penal code for which the state can bring actions against the alleged perpetrators according to the rules defined by the law of criminal procedure.

Both areas of the law involve extensive government and private sector investment in the form of courts, law firms, accountants, investigators, stenographers, transcribers, forensic laboratories, expert witnesses, police, and prisons. Nevertheless, criminal law seems to get more attention because the circumstances surrounding criminal cases make better drama in the news and entertainment media.

A third type of law, administrative law, involves setting and enforcing rules and regulations by government agencies other than the Legislature. For instance, the Texas Commission on Environmental Quality sets pollution limits and imposes fines on violators. Administrative law receives very little attention by the news media or the general public, a situation that sometimes allows powerful interests to exercise considerable influence in this area. Because the primary arena for administrative law is in the executive branch, it is not covered here.