Traffic lawyer Steve Cullen says the test for drug impaired driving needs to be changed.

He told Heather du Plessis-Allan one solution could be a saliva based test on the side of the road.

But he thinks authorities need to look at concentration levels in the blood tests.

He says people getting a blood analysis should only be able to fail if the concentration level in the blood is prohibited.

If there is no concentration level even the mere trace of a drug can be picked up.

LISTEN ABOVE: STEVE CULLEN SPEAKS TO HEATHER DU PLESSIS ALLAN