A Will contest is when someone (especially a close relative, etc.) gets left out of someone else's Will and they want to recieve something, so they "Contest" the Will based upon various reasons in order to try to eliminate the Will from being accepted by the Surrogate's Court. The party who presents the Will for Probate initially bears the burden to prove the Maker of the Will had the testamentary capacity to execute their Will. Once that initial burden of proof is met by proving what's known as a Prima facie case (meaning on its face, its complete and sufficient) for probate, the burden then switches to the objectant to show a triable issue of fact that undermines the original proof of legitimacy.