if they are showing no signs of impairment, why would the cop issue the drug test? you aim for the worst case scenario of a cop enforcing this every time he stops someone. if you didn't want to get caught with an illegal substance in your system, don't use it. And because the compounds are in your system, how can the cop know if you smoked it earlier and are just returning to sobreity or if you smoked it a week ago. The law isn't about just protecting your rights, it's also there to protect everyone else from you and help cops stay alive. I agree it's a little much, but don't blame me for it. If the gov't would read half the shit they passed into law before passing it, you would have better laws.