Is there a "breathalyzer" for marijuana?

[loinburger]

I was just curious if there was a breathalyzer-type device for marijuana (i.e. a device that could be used for roadside tests to determine the intoxication level of a marijuana user), or if such a device would be possible (assuming that blood and urine tests wouldn’t be used as roadside marijuana tests).

[Duck_Duck_Goose]

Well, actually, they’re working on it.

http://www.nlm.nih.gov/medlineplus/news/fullstory_10454.html

US Plans Breathalyzer-like Drug Test for Drivers
Reuters Health

By Laura MacInnis

Tuesday, November 19, 2002
WASHINGTON (Reuters) - Roadside drug tests modeled after breathalyzers are nearly ready for use in the United States to help police identify drivers impaired by illegal substances, officials said on Tuesday.

National Drug Control Policy Director John Walters said the cheap, on-the-spot tests would hasten the arrest of those driving under the influence of illegal drugs like marijuana or cocaine, as well as alcohol.

“Soon officers will have the ability to positively identify someone who is endangering others’ lives on the road,” he told a news briefing at the National Drug Control Policy office. “This is not something we are powerless to do something about.”

Walters said the drug tests were in the last stages of trials, but he declined to say when the new devices would be deployed. Similar technology has also been used in pilot tests in Britain and continental Europe.

[tcdaniel]

Cite forgotten, but I read recently that they may use simple urine test to disclose drug or MJ usage of a suspect driver. Problem is the residual effect can make it difficult to prove you smoked a joint 3 days ago.