As I said, it’s a social determination, and in fact, there isn’t a huge amount of consistency between various court decision for various purposes.
Your wishes, even if they were merely mentioned in passing during conversations, would be considered, of course, but there’s no assurance that even the most carefully framed clause in a will will be honored. That’s explicit in federal, state and common laws and precedents: A will is only a guide. (As a practical matter, it does serve to eliminate some ‘he said, she said’ among your friends and family, and often non-will statements aren’t actually weighed unless the matter goes to court.)
As a general rule, your body belongs to your estate, managed by your executor However, it does not belong to your executor, and cannot be used for his own profit or benefit (unless your executor is also an heir, which is quite common for ordinary estates). However, this general rule is full of holes: for just about every situation where anyone might have an actual interest in the body, there’s case law that covers the situation. "The estate’ owns it as a matter of default, but it doesn’t have a “right” to it [I’m not a lawyer, but I think it’s more proper to say that estates have claims or interests, not rights, anyway)
Take organ donations: no matter how loudly and frequently you declare your wish to be an organ donor; not matter how many stickers you have on your license or how explicitly your wishes are tatooed on your chest, if a close relative (parent, child, spouse, or sometimes sibling) objects, your wishes will be trumped, and no one has any recourse (i.e. AFAIK, no one has ever successfully sued a relative for stopping an organ donation out of personal squeamishness]. As a practical matter, hospitals usually won’t even consder touching a possible controversy.
You can certainly leave your skull to a relative. Just have your remains cremated. Oh, you mean your intact skull? Well, state your intent clearly in your will, but be aware that the diligence of the executor and the superstitions or ‘delicacy’ of a judge will probably decide the matter regardless.
**Let me suggest this: Don’t specify your intention (“Donate my head to Alfredo Garcia!”. Instead specify your desired post-mortem preparation in scientific terms and then specify the disposition of the mineral remains. Make a clear parallel to the practice of cremation (where the ashes are often given to relatives or friends) This will make it seem much more reasonable to the courts.
Russell used the larva of Demestid beetles to clean the flesh off the bones. It’s a standard scientific technique, and most universities or museums will have access to them for research purposes. You might want to cite a more recent paper than Russell (1947), which I just happened to have on file because it’s the oldest cite for this method. The “ossuary” can be any cheap box: historically, ossuaries have often been cheap wood or mortar, but the word sounds ‘special’.
Note that these terms require you to make the arrangements in advance, so the department (or some penuious postdoc like Dr. Desperate) will be willing to handle it (a bequest of a couple of thousand might not be a bad idea). You’d need to do this regardless. It’s not like a Funeral Director will give your sis a raw head, nor can he ship it off to Skullz’R’Us for a quick strip and wax. If YOU don’t make the preparations, they’ll just shrug in confusion, and give you “the usual”.
Your wishes might be a little more legally tight, if you bequeathed your body to the Anthropology Department of Local University “for use in training or study of the current variants in the Demestid method of Russell”, but if Dr. Desperate dies before you (or marries wealthily and retires, or makes a major discovery and gets endowed for the Skull Chair at Evil Conquerors University) and Local University didn’t actually need a training subject, no one might bother to deal with your body. Stuff like that happens at universities. Don’t ask.
Of course this isn’t legal, medical or bioethical advice. It’s just an idea.
