Unconstitutional if refusal has negative consequences. If not, ???
The courts have recently been ruling that when someone is detained by the police that the individual is essentially in custody. In other words, if one is not free to go, or even if one would reasonably believe that to be the case, that person is entitled to be informed of their rights etc.
I’m sure this case will hinge on what the police led the person to believe regarding how “voluntary” their detention and submission to tests was.