An establishment by evidence of the truth or falseness of an alleged fact;evidence upon which a court's judicial ruling is based. burden of proof. 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. standard of proof. Level of proof required to sustain certain actions; vary...