A new tool to help police detect drivers under the influence of illegal drugs was unveiled by the San Diego Police Department. The device, the Drager 5000, will use a sample of saliva to detect drugs in a person’s system. It can detect illegal and prescribed drugs as well. The detection devices will be only one step in determining if someone is driving impaired, and will be used in conjunction with evaluation by officers at the scene as well as blood tests when warranted. DUI Defense Attorney Vik Monder said the test is voluntary. Also, he said because there is not set limitations on the amount of marijuana a person can legally consume before becomming intoxicated, drugged driving cases are difficult to prosecute. He said the evidence often relies on an officer making a subjective decision about how impaired a driver is or is not. Los Angeles Police has used the machines for several years, the chief said, and there is a pilot program going on in Denver, Colorado. It is highly unlikely someone who smoked marijuana days prior to the test would register a result, according to an officer demonstrating the machine.