The board on Wednesday filed a draft rule that would explicitly ban any business with a liquor license from allowing marijuana use on site.
Among the board's concerns is that people who use marijuana in combination with alcohol could pose an extra danger on the roads if they drive.
It's already illegal under Washington's recreational marijuana law to use pot in public, and that includes restaurants, bars and clubs. But at least a couple of establishments have tried using loopholes to allow customers to use marijuana, such as by having "private clubs" within the businesses.
One is Frankie's Sports Bar and Grill in Olympia. Owner Frankie Schnarr says he'll fight the rule because it would hurt his business.
He says that if people aren't allowed to use pot inside, they'll just go outside, and he'd rather be able to keep an eye on what they're doing.