THC illegal and make no effort to accommodate it. In Colorado, which may legalize marijuana in a public vote this November, the state Legislature came within one vote earlier this year of setting a standard of 5 nanograms. That standard was put into I-502 so Washington voters, who are rightly concerned with road safety, would approve the rest of the bill. The rest of the bill makes a lot of sense, and voters should be willing to try the 5-nanogram standard and see how it works. It still requires a traffic stop, probable cause for impaired driving, the calling of a separate drug officer to examine the driver and the drug officer's decision to administer a blood test. Those things are time-consuming and expensive, and are not likely to be done indiscriminately. And recall that the blood-alcohol standard was 0.15 percent for many years before it was eventually lowered to .08. If the 5-nanogram standard turns out to be wrong, it can also be changed.