A terrible idea. Seems to me they already have the authority to arrest the person, take them to the hospital, and have the blood drawn. Exposing the cops to all that potential liability just doesn't make sense. I was a Critical Care Registered Nurse for 6 years and saw several cases where even experienced phlebotomists left hematomas behind. It just happens. All it takes is for the person to twitch a little bit at the wrong time. And that was on people who were cooperating. Having cops doing it forcefully, IN THE FIELD, introduces way too many issues. To me, this is a no-brainer.