What is the legal burden of proving due execution, knowledge and approval and testamentary capacity in a will?

The propounder of a will has the legal burden of showing due execution, knowledge and approval and testamentary capacity. Once there is evidence of due execution and of the will having been read over by the testator, a rebuttable presumption exists that the testator knew and approved of the contents of the will: Vout v. Hay, 1995 CanLII 105 (SCC), [1995] 2 S.C.R. 876, at para. 26.

Where suspicious circumstances exist, however, the rebuttable presumption that the testator knew and approved of the contents of the will no longer applies. In such circumstances, the propounder of the will assumes the legal burden of proving knowledge and approval. If the suspicious circumstances relate to mental capacity, the propounder of the will also assumes the legal burden of establishing testamentary capacity: Vout v. Hay, 1995 CanLII 105 (SCC), [1995] 2 S.C.R. 876, at paras. 25-27.