MONTGOMERY COUNTY’S government unions, which for decades amassed powers unique even in the pro-labor state of Maryland, had their wings clipped when the recession forced local officials to roll back privileges — and blatant abuses — that bilked taxpayers and tied the hands of public agencies. Now, in a fit of petulance, the unions are striking back at their paymasters — elected officeholders — by boycotting and picketing the local Democratic Party’s annual fundraiser this weekend.

This is not an instance of hardscrabble coal miners protesting intolerable conditions, nor of poor field hands standing up against exploitative farm bosses. state-of-the-art agency a front-runner in next year’s gubernatorial race The trigger for this protest, and for the unions’ fury, is a 2011 law that was enacted unanimously by Montgomery’s all-Democratic County Council. The law scrapped rules that allowed the police union to haggle endlessly over routine management directives — even one that requires officers to look at their county e-mail daily.

The police union forced the issue onto the county ballot last year, arguing misleadingly that the law eliminated collective bargaining. In fact, it simply put Montgomery’s police on the same footing as other police departments in Maryland that have the right to bargain collectively. The police lost the referendum resoundingly; in one of the most pro-labor localities in the United States, about 60 percent of Montgomery voters elected to uphold the law. But rather than accept the voters’ judgment, the county’s unions have upped the ante by attacking the Democratic Central Committee, which backed the law.

The field of battle is an odd one: the party’s Spring Ball, a soiree whereelected officials, precinct workers and key supporters (including union chiefs) dance, rub shoulders and raise money — usually about $50,000. Under pressure from the unions, which asked elected officials not to attend, the ball looks like it will be a bust. Key party leaders, including Lt. Gov. Anthony G. Brown,Sen. Benjamin L. Cardin and state Sen. Brian E. Frosh (Montgomery), who is weighing a race for attorney general next year, have said they’ll honor the unions’ boycott and picket.

Some Democrats say they will not cross a picket line “on principle.” But exactly what is the principle they’re upholding? An absurd rule, unmatched in other police departments, that was rejected by 60 percent of Montgomery voters? In this case, the “principle” at stake looks more like political cowardice.

It is particularly troubling in the case of Mr. Brown. If he can’t stand up to bullying by arrogant special interests — even to attend a fundraiser by his own party — what kind of spine can Marylanders expect from him as chief executive?