The problem with drugged driving is that people are doing it with a combination of legal and illegal drugs, sometimes at the same time. Furthermore, driving while on drugs does not carry the same social stigma and barometer as drunk driving. There is no clear “0.08 percent” line that shows when it is safe and unsafe to drive.
Due to the variable nature of drug use, it is difficult to collect data and track trends to come up with solutions. At this point, officers rely on their observations to determine if a person is capable of driving or not. This leaves you at the mercy of the police officer that pulls you over. There is no bright-line that you can point to that demonstrates you are competent to drive.
If you were pulled over for driving while drugged, then you may want to contact a criminal defense lawyer. Drugged driving is still illegal, even if the legal and law enforcement landscape is still evolving. There are several ways to contest them, but they are still quite serious.