Oregon's largest district attorney's office announced Monday that it would dismiss pending cases involving violation-level marijuana possession in light of Measure 91's statewide passage last week.

Multnomah County District Attorney Rod Underhill's office released a statement to The Oregonian on Monday afternoon, saying prosecutors will dismiss a total of 50 pending marijuana cases. All involve marijuana-related activities that will be legal when the new law becomes effective for possession and cultivation July 1, 2015.

Measure 91, which allows anyone 21 and older to possess certain amounts marijuana and creates a state-regulated system for producing and selling the drug, won Multnomah County with 71 percent of the vote.

"Because it is clear that a significant majority of voters in Multnomah County support the legalization of marijuana in certain amounts, this office will dismiss the pending charges related to conduct which will otherwise become legal July 1, 2015," the statement reads. "Any remaining charges not impacted by Ballot Measure 91 will be prosecuted."

Of the 21 cases reviewed by the office, 18 are violation-level offenses -- possession of less than an ounce has been treated as a non-criminal violation. The remaining three were charged as crimes.

Another 29 involve warrants for marijuana-related crimes, including 23 violation-level possession offenses. Those 29 warrants also were dismissed.

According to the statement, the office will not prosecute "future charges for conduct related to marijuana possession and delivery of marijuana which will become lawful under Measure 91 absent exceptional circumstances."

Leland Berger, a Portland attorney and marijuana legalization advocate, applauded the decision, calling it “good news” for advocates who have pushed for legalization. “I appreciate their responsiveness,” Berger said.

Prosecutors in other counties have said they are still considering how to respond to Measure 91's passage.

-- Noelle Crombie