Laycock cited a previous case from Sandy, saying the fifth amendment applies only to speech. Utah law grants people the right to refuse a sobriety test, but anyone who refuses can be stripped of their driver's license.Just a wild guess, but Sandy City got it from the US Supreme Court?
Schmerber v. California, 384 U.S. 757 (1966), held that a State could force a defendant to submit to a blood-alcohol test without violating the defendant's Fifth Amendment right against self- incrimination. We now address a question left open in Schmerber, id., at 765, n. 9, and hold that the admission into evidence of a defendant's refusal to submit to such a test likewise does not offend the right against self-incrimination. South Dakota v. Neville, 459 U.S. 553 (1983).
http://caselaw.lp.findlaw.com/cgi-bin/getcase.pl?court=US&vol=459&invol=553
