Is Marijuana the Next Step for Ignition Interlocks?

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Marijuana interlocks could be available in the future

Ignition Interlock device makers are developing a new area of detection –marijuana.  At present, cannabis or THC ignition interlock devices are available to law enforcement only.  But interlock companies do not rule out that, at some time in the future, we might see ignition interlock devices that prevent one from driving when THC is detected.

Unlike alcohol, marijuana can’t yet easily be measured by breath.  There are companies working on this technology but it is not yet readily available.

Additionally, people react differently to THC levels. With alcohol, there’s a direct correlation to the percentage in the blood and the impairment to the user.  With marijuana, you can consume very little and be very impaired or consume a lot and be unimpaired.

Currently the main way to get a sample to test THC levels is through sweat or saliva.  So there’s a question on whether it’s even constitutional or unreasonable search and seizure to get a test sample.

But as more states legalize marijuana, they want to be able to assess if it is contributing to traffic accidents.  Dräger offers a portable device that can be used by law enforcement, but said an ignition interlock device might be feasible in the future.  “It is possible. However, we expect the desire is greater for a device that detects multiple different drugs which can cause impairment [for an interlock],” said a spokesman.

Dräger DrugTest 5000 uses a saliva swab to detect 7 different drugs.  This includes detection of the main psychoactive component in cannabis. But at preset, this technology is not suited to a consumer-facing interlock device.

Directed is working on a device that might be used by individuals as well as law enforcement, it said.

Advancements in technology may permit an actual breath test for THC in the future.  Last July, a University of California–San Francisco study found that THC could be detected in the breath for up to three hours after smoking.  The study was sponsored by Hound Labs that is seeking to develop a dual alcohol and THC breathalyzer for law enforcement use.  However, the company has no plans as of yet to offer it as an interlock, it said.


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