cannabis and driving,

Clinical study tests how cannabis affects volunteers’ driving skills – Marijuana News

Dr. Robert Mann at the Centre for Addiction and Mental Health in Toronto is trying to determine the relationship between marijuana consumption and driving ability, using a “state of the art” simulator.
One toke over the line: Race on to develop 'pot breathalyzer'

Natalie Grover ~ Reuters ~

As cannabis bans are relaxed in more U.S. states, the race is on to develop an instant roadside breathalyzer for police to test drivers who may be taking the "high" road.