There was an episode of Law & Order SVU called Rooftop where a suspect refused to have his blood drawn for a DNA test and said it was because he was a jw. The detectives asked him to prove it, but the M.E. said that so long as he said it, she had to take his word for it and couldn't do the test.
I didn't know that jw's would against a DNA test, and of course, the guy was just saying that to get out of taking one for what it would prove.