Perhaps the Will is just plain ambiguous and you need the extrinsic evidence. Will is plain wrong and did not say what the testator wanted. When Should Extrinsic Evidence Be Excluded? Unwieldy Unreliable (maybe a devisee lies, maybe the testator was a filthy liar) Judges and Juries are not in a good position to be able to rewrite a will, which is what will have to happen once you start admitting extrinsic evidence. Threat of malpractice Best evidence of testator's intent is the will. Will is a safe harbor Flood of litigation would follow. Judges and juries are inevitably biased. They have their own ideas about how the estate should have been distributed. The Common Law Answer: Plain Meaning Rule: Exclude it unless there is am ambiguity? If there is ambiguity, you can let stuff in. There's a difference between patent and latent ambiguities. Patent is obvious and appears right on the face of the will. A latent ambiguity (good luck figuring it out) is where you read the will and it makes sense, but then you go to distribute property, you realize that the will doesn't seem to fit the world. Maybe the testator leaves property to people who don't seem to exist. Problems with PMR Doesn't solve problem of when the will is just plain wrong. Mahoney case. Guy wanted to leave stuff to his twenty-five cousins. Lawyer said in will that he left to heirs. Turns out, his heirs weren't the twenty-five cousins. No ambiguity. Guy wants his money to go to the Scottish Society for Prevention of Cruelty to Children. The lawyer left out the "Scottish." No ambiguity, thus no extrinsic evidence. California Russell case: You can allow in extrinsic evidence certainly to clarify a patent ambiguity. You can use extrinsic evidence to reveal and resolve a latent ambiguity. But then, Cal declared that there was no ambiguity--it was clear because of the evidence, so no extrinsic evidence to resolve the ambiguity--lady wanted half to guy and half to dog. Well, half to dog is invalidated and half goes to niece even though extrinsic evidence was clear that she wanted it all to go to the dog.
Perhaps the Will is just plain ambiguous and you need the extrinsic evidence. Will is plain wrong and did not say what the testator wanted. When Should Extrinsic Evidence Be Excluded? Unwieldy Unreliable (maybe a devisee lies, maybe the testator was a filthy liar) Judges and Juries are not in a good position to be able to rewrite a will, which is what will have to happen once you start admitting extrinsic evidence. Threat of malpractice Best evidence of testator's intent is the will. Will is a safe harbor Flood of litigation would follow. Judges and juries are inevitably biased. They have their own ideas about how the estate should have been distributed. The Common Law Answer: Plain Meaning Rule: Exclude it unless there is am ambiguity? If there is ambiguity, you can let stuff in. There's a difference between patent and latent ambiguities. Patent is obvious and appears right on the face of the will. A latent ambiguity (good luck figuring it out) is where you read the will and it makes sense, but then you go to distribute property, you realize that the will doesn't seem to fit the world. Maybe the testator leaves property to people who don't seem to exist. Problems with PMR Doesn't solve problem of when the will is just plain wrong. Mahoney case. Guy wanted to leave stuff to his twenty-five cousins. Lawyer said in will that he left to heirs. Turns out, his heirs weren't the twenty-five cousins. No ambiguity. Guy wants his money to go to the Scottish Society for Prevention of Cruelty to Children. The lawyer left out the "Scottish." No ambiguity, thus no extrinsic evidence. California Russell case: You can allow in extrinsic evidence certainly to clarify a patent ambiguity. You can use extrinsic evidence to reveal and resolve a latent ambiguity. But then, Cal declared that there was no ambiguity--it was clear because of the evidence, so no extrinsic evidence to resolve the ambiguity--lady wanted half to guy and half to dog. Well, half to dog is invalidated and half goes to niece even though extrinsic evidence was clear that she wanted it all to go to the dog.