Cause
The word cause has several meanings in the area of law. At its most basic, a cause is the reason, or grounds for bringing a lawsuit or filing criminal charges in the first place. In the case of the former, the cause can be an injury, a wrongful death, a monetary loss, loss of or damage to property, loss of income or employment or - in the case of slander or libel - damage to one's reputation.
In the case of a criminal charge, the cause is reasonable suspicion that the one being charged with the crime is indeed the perpetrator.
Once the trial is underway, cause takes on a slightly different meaning; it refers to an action or situation that brings about an effect or result. In a civil case, this might be negligence that caused the plaintiff's injury or loss. In a criminal trial, it usually refers to the cause of a victim's death in a murder case (a specific injury inflicted by a particular weapon).
A cause may be the reason or justification of an action or state of being. A law enforcement officer may stop a driver and search the vehicle for probable cause; an employer may terminate an employee for good cause; a party or counsel may have reasonable cause to believe an assertion or statement, etc. These causes are usually determined on a case-by-case basis.
Contracts may also be terminated or made null and void for cause; however, this cause varies from one state to another. Civil law in the state of Louisiana for example differs from the other 49 states in significant ways because of its basis in Napoleonic Code. Contracts in Louisiana can be voided for reasons of immorality, or because the original basis of the contract becomes invalid.