Driving under the influence (DUI), or driving while intoxicated is a criminal offense in Nepal. Nepal traffic police started this rule years ago and since then drinking and driving case have reduced a lot. The number of accidents have also reduced in recent years.
Now they are trying to control people who smoke marijuana and drive.
According to -नयाँ पत्रिका- a daily Nepali newspaper, Nepal traffic has started checking if people are driving under the influence of drug besides DUI. They said some cases of accidents have slightly increased in Bhaktapur Nagarkot area which was not caused by alcohol consumption but due to the influence of marijuana. If they catch someone driving a vehicle smoking marijuana then the police will cease the license.
It will hard to tell if a person has smoked marijuana or not. A breathalyzer does its best job to show if a person has consumed alcohol. But finding out if a person has smoke marijuana is nearly impossible task unless the person is carrying marijuana.
Smoking marijuana in Nepal is illegal. So even though if you are caught smoking it you will get served by policemen.