Unlike an “ordinary” civil suit, the evidentiary burden in an estate contest based on incapacity is often on the defendant to prove that the signer had the requisite capacity.
In a lawsuit challenging a trust based on testamentary incapacity, the proponent of the document must establish due execution and that the person signing had sound mind. Cima v. Rhoades, 416 S.W.3d 320, 323-24 (Mo. Ct. App. 2013). As such, the party seeking to establish that a trust or trust amendment exists must prove that the settlor had adequate capacity. Rourner v. Wise, 446 S.W. 3d 242 (Mo. 2014).
Similarly, in a lawsuit challenging a beneficiary designation (e.g., transfer on death), the party requesting enforcement has the burden or proving the existence of a valid contract by clear and convincing evidence. J.H. v. Brown, 331 S.W.3d 692, 699 (Mo. Ct. App. 2011).