If you leave it behind....

....it's mind to find. (OK, so I'm no Johnny Cochrane.)

Fourth Amendment Doesn't Protect Spit on the Sidewalk: Facts: Rape suspect walking on a street spits on the sidewalk. An investigator is following the suspect, and he collects the spit; a DNA test proves a match. Holding: No Fourth Amendment violation.

[A]lthough the defendant had a reasonable expectation of privacy in his saliva (and other bodily fluids), see [citations] when he expectorated on to a public street and did not retrieve the fluid, he voluntarily abandoned that protection; he assumed the risk of the public witnessing his action and thereafter taking possession of his bodily fluids.