Burden of proof is the duty incumbent on a litigant to prove to the court the fact or facts supporting the claim at issue. First, there is the burden on the plaintiff to tender evidence in support of the claim he has put forward. Secondly, there is the persuasive burden, the onus of convincing the court on the facts at issue: this remains constant throughout the trial with any litigant on whom the burden of proof lies, be he plaintiff or defendant.