The union that represents Portland, Ore., police officers filed a grievance Thursday challenging a voter-approved measure to create a civilian oversight board. 

The Portland Police Association, which represents 850 officers, contends that matters related to discipline, discipline standards, due process, personnel files and criminal and administrative investigations must be negotiated with the city. 

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"The city's conduct to evade its contractual obligations through voter enacted Charter changes is repetitive and egregious," the union said in the grievance to Deputy Police Chief Chris Davis. 

Measure 26-217 passed Tuesday with 82% of the vote. The initiative will create a civilian board with powers to investigate police use of deadly force and alleged officer misconduct. The commission would also have subpoena powers, and could discipline and terminate officers. 

It would operate independently of the city and would receive no less than 5% of the police budget, OregonLive.com reported. The police union said the board wouldn't be held accountable since it would not report to the City Council, the newspaper reported. 

The measure was backed by City Commissioner Jo Ann Hardesty, who previously said she anticipated a lawsuit from the union. 

Messages to her from Fox News were not immediately returned. 

In the grievance, the union cited court rulings in 2010 and 2016 by the Employment Relations Board that rejected attempts by the city to allegedly evade bargaining obligations with the police union.

The union asked that the city restore the "status quo," and rescind any discipline and policy recommendations issued by the board.

Police cuts rejected

The grievance came on the same day city commissioners narrowly rejected a budget amendment that would have slashed $18 million from the Portland Police Bureau in a 3-2 vote. Hardesty also proposed the amendment. 

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“The testimony we’ve heard is clear: The status quo is unacceptable," said Mayor Ted Wheeler, who also serves as police commissioner. Wheeler was reelected Tuesday despite a contentious first term.

"Many Portlanders, and most of the people who testified about this item, do not trust the current criminal legal system — they do not trust the Police Bureau,” he said, adding that he nonetheless felt cutting the police budget further was not the solution.

Portland has been roiled by five months of almost nightly protests that have routinely devolved into unrest in the city's downtown. 

The Associated Press contributed to this report.