actually, your doctor can't run the test either. It is not a waived lab test in most states and requires a technician with special certification.
When I wrote that post I was implying you send them back to the clinic if they have not made any contact with their physician and the office (which would hopefully have a certified tech on staff) would run the screen. Obviously this is time dependent (although I'm not sure exactly how long after use such drugs are still detectable in the urine) and this isn't by any means the accepted norm. I was just proposing it as a solution to the problem. If it is someone abusing the meds they will likely just sit and wait for their script to mature (or maybe try to go scam someone else), and if not they would likely pass the screen and get a new script (which was the part of the post which implied they return to their physician, but as it came at the end of the post I can see where the confusion lays).
In my future practice I wouldn't consider this to be all that unreasonable. Some people may raise a fuss and try to cite things about unreasonable search and seizure protection (which has occurred in other cases where drug testing has been brought up) but IMO people are not entitled to narcotics and are certainly not entitled to refills after irresponsible behavior with their current batch. With another script ripening it would be hard to make any case that someone is trying to compel a drug test. It is an opt in situation. I only mention this because it is the only counter argument I can think of to sending the patient back to the clinic for a quick screen and a fresh script if clean.
As far as the other part goes, if the doctor signs off on it (I believe) you absolve yourself of any liability. Sure, there are "pill mill" docs out there. I wouldn't begin with the phrase "With all the...." it sounds biased and a little jaded, although you may live in an area where it happens more often

But on the other hand, refusing to fill a script on your own opinion or suspicion of "pill milling" may carry consequences. There are already
precedents for job loss or discipline for refusing to fill a doctor's orders. The waters get foggier with opioids, and maybe there are some laws or rulings which cover this already that I am not aware of. But from my point of view, I know that a physician can be successfully sued for pain and suffering in denying a patient pain meds who they wrongfully suspect of seeking, so I would assume a pharmacist who suspects either the doc or the patient is also not immune.