"Paul Cassell, a criminal law professor at the University of Utah’s S.J. Quinney College of Law, wrote in an opinion piece for The Salt Lake Tribune that state law doesn’t permit a blood draw in this situation — especially since the blood was being sought to prove the patient was not under the influence."  from the DP article
I'll go with the professor's opinion over yours.
.
Using the word mandatory is a fault.  Only if consent or a warrant is granted by a judge.  Warrants are not mandatory or manufactured.