An anonymous reader writes with this news from Tacoma, WA's News Tribune: A team at Washington State University is working to develop a breath test that could quickly determine whether a driver is under the influence of marijuana. Law enforcement officers already use preliminary breath tests in the field to estimate drivers' blood alcohol content. But no similar portable tool exists to test for marijuana impairment ... Stoned drivers have become an increasing concern since Washington voters legalized recreational use of marijuana ... A quarter of blood samples taken from drivers in 2013, the first full year the initiative was in effect, came back positive for pot. ... officers and prosecutors rely on blood tests to determine how much active THC is present in a driver's blood. Those test results aren't immediately available to patrol officers who suspect someone is driving high." Also reported: "Under Washington's legal marijuana law, those who get caught driving with a blood content of at least 5 nanograms of active THC per milliliter are subject to an automatic driver's license suspension of 90 days or more."