The new law makes it legal for adults to possess up to 1 ounce of marijuana, but illegal for that same adult to drive if the THC content of his blood reaches 5 nanograms per milliliter.

Steve Sarich, who uses medical marijuana for back pain, says he wakes up at four to five times the legal limit. Six weeks ago, he said that if the legalization initiative passed — along with the new DUI standard — he'd either have to hire a driver, or leave Washington.

See full article here: http://www.npr.org/2012/12/05/166531388/pots-legal-in-washington-state-but-dont-drive-high