There are no standards like with liquor.

I would just keep a small amount of pills with me in a properly labled bottle.

I would judge the cop's reaction if he did find a pain med bottle on you. Sometimes you can just be honest and say that you carry them because my life depends on this medication or for an emergency.
Othertimes, if the cop was a jerk by his general attitude, I would lawyer up.

I don't think a field test would do much good to convict because meds stay in your blood for a while.

Best thing is to drive with more awareness and be more viligent in obeying traffic laws when carrying the type of medications that could cause you problems.

And if you did go to court, probably enough people either has been or known someone in a similar situation or has enough sense to understand the stiuation and not convict like with drunk driving. Most people view medications that are prescribed to you as a necessity and can relate. But a jury is going to be less sympathetic to someone well over the legal limit because of liquor.

But I figure that some company will one day find a fool-proof system to detect those that are 'over thelimit' on perscription or even OTC meds. Technology is great.

This thread produced some really great ideas. Thanks for all the replies. The floor is yours now. I'm signing off.