That confidence was tested, however, when a D.C. police officer placed samples of his product in a disposable field test and it turned purple — the color traditionally indicating marijuana.

That confidence was tested, however, when a D.C. police officer placed samples of his product in a disposable field test and it turned purple — the color traditionally indicating marijuana.

What marijuana impairment looks like and how it can be measured are questions that continue to elude police and scientific ...

Because there’s no breathalyzer test to immediately determine whether someone is under the influence of marijuana, police departments use a different tool, drug recognition experts, or DREs.

Sherman Police Chief Joel Spellins is spending part of his week teaching area law officers to observe, identify and articulate signs of impairment.

Identifying them takes a field sobriety test. Oakland-based Hound Labs want to make that easier. It has been working on a breathalyzer for pot that measures the amount of THC in a person's breath.