Interesting Fourth Amendment Question:
If the police want to collect a suspect's DNA sample, can they mail him a letter under false pretenses, wait for a response, and then analyze the seal on the letter (which the suspect likely sealed with saliva) to collect the DNA, all without a warrant? A divided Washington Supreme Court has just concluded that the answer is "yes" in State v. Athan (see pages 20-25). Howard has links to the various opinions in the case here.