The threshold of legal capacity to sign a will is much lower than what is required to sign other documents. According to the law firm of Dutcher and Zatkowsky, a testator, or the person making a will, does not have to know what year it is in order to legally sign it, but he would not have legal capacity to sign a business contract.
Most states have three-pronged criteria to measure legal capacity in regard to wills. According to the New York Court of Appeals, a testator must only generally understand what she owns and her relationship with the person she is giving each asset to. She must also be able to grasp the connection between her beneficiary and the asset, and the fact that she is transferring ownership to him when she dies.
According to Dutcher and Zatkowsky, a testator needs only one lucid interval when signing his will for the will to be valid. He does not have to have any recollection of signing the will the next day. The American Psychological Association puts the onus on attorneys, suggesting that they watch for “red flags” such as memory lapses or problems communicating during the signing process and stop the process if necessary. But this doesn’t offer recourse for heirs years after the testator’s death.
The American Bar Association indicates that because there is such a range of intellectual capacity between individuals to begin with, it is virtually impossible for the law to give a specific definition of legal competency or to draw an immutable line beyond which someone lacks capacity. If you find yourself in the position of having to prove that a loved one did not have legal capacity at the time he made his will, the University of Oklahoma College of Law indicates that “unnatural disposition” sometimes sways the courts — glaring instances where the testator might give his entire estate to a church in another country that he never visited, for instance. Other standards include creating an inference that the testator wasn’t lucid at the time of the signing by proving he was rarely aware, such as if he were a chronic alcoholic and usually intoxicated, or if he suffered from dementia that was diagnosed years before his will was made and which could have been expected to progress.