U.S. District Judge James Robart, pointedly reacting to the Seattle police union’s rejection of a tentative contract, said Monday he would not let the powerful labor group hold the city “hostage” by linking wages to constitutional policing.

“To hide behind a collective- bargaining agreement is not going to work,” Robart said during a dramatic court hearing he opened by laying out a path for police-accountability reform and closed with an emotional declaration that “black lives matter.”

Robart, who is presiding over a 2012 consent decree requiring the city to adopt reforms to address Department of Justice allegations of excessive force and biased policing, called for major changes that would directly affect the union’s membership: streamlined appeals of officer discipline and internal investigations conducted by civilians rather than sworn officers.

Robart ended the hearing with deeply personal remarks, in which he noted a statistic that showed, nationally, 41 percent of the shootings by police were of blacks, when they represented 20 percent of the population, the Seattle Times reports.

“Black lives matter,” he said, drawing a startled, audible reaction in a courtroom listening to the words coming from a federal judge sitting on the bench.

He also said the recent shootings of police officers, including in Dallas, Baton Rouge and, in 2009, of four Lakewood, Pierce County, officers, reflected the importance of the work being done to heal police and community relations.