New breathalyser will detect whether drivers are stoned

Up until now, it’s been difficult for police officers to tell if a driver is stoned – there is no roadside breathalyser test for marijuana, similar to the one for alcohol.

Officers have to rely on tests such as making suspected smokers walk in a straight line or count to 30 – or relying on blood tests which can take days to come back from the lab.

But that could be about to change.

Chemistry researchers at Washington State University have devised a portable gizmo which can detect THC – the active ingredient in cannabis – in people’s breath.

The device uses ion-mobility spectrometry, the same technology used in airports to detect drugs and explosives.

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The gadget will not be able to tell how stoned a driver is – just that they have consumed marijuana. Police officers will then take a blood test for use in court.

A prototype is due to be finished by Christmas, according to the researchers – and human tests will continue throughout 2015. There’s no date fixed for when it will first be used on the street in the UK.