Nearly two decades after voters passed a medical marijuana law that often left the police, prosecutors and even patients confused about what was allowed, Gov. Jay Inslee signed a bill on Friday that attempts to clean up that largely unregulated system and to bring it in line with Washington’s new recreational marijuana market.
Among the law’s many provisions, it creates a voluntary registry of patients and, beginning next year, eliminates what have become in some cases large, legally dubious “collective gardens” providing cannabis to thousands of people. Instead, those patients will be able to buy medical-grade products at legal recreational marijuana stores that obtain an endorsement to sell medical marijuana, or they will be able to participate in cooperatives of up to four patients.
And those big medical marijuana gardens will be given a path to legitimacy: The state will grant priority in licensing to those who have been good proprietors.
The proliferation of medical dispensaries has long been a concern for the police and other officials who denounce them as a cover for black-market sales. Washington in 1998 became one of the first states to approve the use of marijuana for medical purposes, but the initiative passed by voters did not allow commercial sales.
Medical marijuana growers repeatedly sought legislation that would validate their businesses, coming closest in 2011, when the Legislature approved a bill to create a licensing framework for medical dispensaries. But Gov. Chris Gregoire vetoed much of the measure.
This time, with the state seeking to support its nascent recreational marijuana industry after the passage of Initiative 502 in 2012, there was a financial impetus to pull the medical users into the recreational system.
Under the new law, patients who join the voluntary registry will be allowed to possess three ounces dry, 48 ounces of marijuana-infused solids, 216 ounces liquid and 21 grams of concentrates.
A version of this article appears in print on April 26, 2015, on page A21 of the New York edition with the headline: State Revisits Rules on Use Of Marijuana As Medicine.