It'll be just a short time before this is overturned. Fingerprints are non-testimonial. So is a photograph of your face. So is a sample of your handwriting. You can be forced to give a handwriting sample. As to polygraphs, at the federal criminal level, they have been approved in only one federal circuit, and then only under limited circumstances. See, U.S. v. Picinonna. Despite this federal non-acceptance, they are widely used at the federal administrative level for security clearances and the like. In the private sector, there are little restrictions on their use. You could also use divining rods, tarot cards, crystal balls and similar implements to discover the truth of a statement if you wanted to. However you can't weight a person down and throw him in the lake to see if he floats.