Look up 929 F.2d 990 United States v. Reid. Pay particular attention to lines 12-15. It pretty much sums up how such a test can be performed without warrant or voluntary consent, or in this case while waiting for an attorney (which would apply as the clock is ticking and they couldnt wait etc). And something tells me Op is not being completely honest in his stating the facts of this situation as i'm hard pressed to believe law enforcement would go to such lengths for a guy who "sometimes took more than directed" of his prescribed meds. I think we're being what my hubs calls "hosed" by OP.Carl, I understand what you are saying. Physical evidence is not testimony, but in the absence of the spoken word, the blood was still used to incriminate him. There would be no other evidence except for a visual inspection by the officer. The blood draw certainly makes for a stronger case. Since he did not consent it still seems like he was forced to incriminate himself. I understand it is metabolizing therefore exigency circumstances exist. But come on, being held down and forced to give a fluid for such a thing is just wrong. In my state being under the influence alone is not a crime, although disorderly conduct of course is. The law may very well be on your side, as i have not investigated it. Just sees like the opposite of freedom. Although since o.p. was legal in taking the drug this might be for nothing, I just wasn't aware some or most states had and supported those laws.
Oh, and yes Op may have been legal in taking his medication but the illegal part comes into play when OP abuses such medication thus becoming impaired and subsequently "under the influence"