it is true you can drive etc while on pain meds BUT in all states the is a violation called:
Operating while imparied...
they LEO use this as an umbrella offence. it is very difficult to beat. because unless the offender has witness it is your word againset the LEO. and from expirence the judge (unless jugde dose not trust the officer)will always beleive the officer over the offender. I know as a paramedic I often testified for "operating while impared" charges. and guess what, every offender was found guilty

so dont under estimate the tricks and loop holes of the law.
the government has an unlimted pocket us regular people dont we have to borrow mogtage and beg for help.