proof legal definition

An establishment by evidence of the truth or falseness of an alleged fact; evidence upon which a courtÂ’s judicial ruling is based.

The responsibility placed on one party to bring forward evidence in support of his cause; as to a plaintiff (in a civil case) or a prosecutor (in a criminal case), the requirement of bringing forth sufficient evidence to support a finding in favor of plaintiff or the state. 

Level of proof required to sustain certain actions; varying levels of proof required include “beyond a reasonable doubt” (criminal cases), “by a preponderance of the evidence” (most civil cases), “clear and convincing evidence” (certain civil and some criminal cases, including fraud).