A prominent D.C. labor law firm got a taste of the other side of the fence yesterday as 15 of its employes picketed its office, calling the firm "unfair to organized labor."

The 17-lawyer firm Bredhoff & Kaiser, one of the most prominent labor law firms in the country, represents numerous unions including the U.S. steelworkers, the National Education Association, hotel and restaurant employes unions and police unions.

It also represents the AFL-CIO's Industrial Union Department, the umbrella organization of the Office and Professional Employes International Union, which is the union picketing Bredhoff & Kaiser.

The 15 firm employes organized by that union are legal secretaries, receptionists, paralegals, and messengers. One of the picketers, Cheryl Gannon, a paralegal at the firm, said there has been "a lot of dialogue but very little movement" in the last six months of bargaining over a contract.

As she spoke, one of the picketers walked by with a sign that said, "Bredhoff & Kaiser works on everybody's labor problems but its own."

Bredhoff & Kaiser partner Robert M. Weinberg, who said he was deluged yesterday with reporters calling for a "man-bites-dog story," said he was "a little bit surprised by the picketing." But Weinberg said he was not embarrassed and not "even chagrined by it."

Weinberg said the picketing surprised him because he was "looking forward to getting successful resolution of all points" and that both sides "are very close to agreement on all major noneconomic issues." Weinberg said the firm voluntarily recognized the union in October 1982 as the bargaining agent for its employes and had "agreed to all the basic things that unions fight for," such as union security and dues checkoff provisions.

John R. Foley, an Office and Professional Employes Union lawyer, said the "peaceful picketing" was necessary because "it was disgraceful that after six months there is still no contract with the firm."

Kathy Kocan Moore, a representative of the Office and Professional Employes Union, said the Bredhoff, Kaiser group was the first from this area to be unionized in a drive to organize thousands of employes at law firms in this area. Union leaders accuse the firm of being "anti-union and intransigent" and of stalling the negotiations.

"We are neither anti-union nor intransigent," Weinberg said, and he denied that the firm had been stalling.