In the wake of legalizing marijuana, Colorado has made an effort to step up training for state troopers in order to better spot stoned drivers.
Troopers will take part in a nine-day course on how to recognize drivers under the influence of marijuana.
Police said the training is needed because stoned driving can be much tougher to spot than drunk driving. Some of the tests for pot and alcohol impairment are similar including the one-leg stand and finger-to-nose examinations.
Colorado troopers reported 60 people were cited in January for pot-related driving offenses.
That makes up about 15-percent of the month's impaired driving citations.
The extra training is funded partially through a grant from the National Highway Traffic Safety Administration.