This came up when I signed up for cryonics. Interestingly, Alcor requires that you donate your body on death to their organization for research purposes, and they will not operate on you (what they believe to be a life-saving procedure) until you are legally declared dead. The reason is precisely that cadavers for medical research are basically entirely unrelated and are classified as private property, not human remains. So Alcor (a cryonics organization that strives to preserve its 'patients' for future revival) insists on having its patients declared dead and and donated so as to not be considered human remains, so that they can save the essence of what makes you human. A clever trick.