Methods for testing the level of a driver’s possible impairment from marijuana is more complex than a simple blood level of the substance. Some states in which marijuana is legal are apparently using tests which could produce flawed results. Other states are set to follow their example.
The foundation recommends replacing the laws with ones that rely on specially trained police officers to determine if a driver is impaired, backed up by a test for the presence of THC rather than a specific threshold. The officers are supposed to screen for dozens of indicators of drug use, from pupil dilation and tongue color to behavior. Study: No scientific basis for laws on marijuana and driving
Here is yet another example of a traffic safety problem which could be addressed more effectively through a White House Vision Zero Task Force. Then, once such a Task Force were to recommend an appropriate law and testing technique, all states could be required to follow suit–without having to reinvent the wheel 50 time over.