Spit and Justice

Orin Kerr poses an interesting 4th 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...

And it happened. More context here.