A mid-level appellate court has ruled against Mayor Bloomberg in his longstanding dispute with the City Council over which unions should be present when it comes time to hash out contracts with municipal workers.

The court’s 3—2 ruling upholds a 2001 City Council ordinance that exempted paramedics and fire-alarm dispatchers from the city’s collective-bargaining negotiations. Under a collective-bargaining agreement, the mayor is able to reach a contract without the consent of each union representing a particular type of employee.

The 2001 council ordinance at the center of the lawsuit required the mayor’s administration to negotiate individually with the two unions that represent paramedics and fire alarm dispatchers, the Local 2507 and the Fire Alarm Dispatcher’s Benevolent Association.

The court found the ordinance did not impinge on the mayor’s authority to negotiate with municipal employees.

Mayor Bloomberg and his predecessor, Mayor Giuliani, have fought hard to keep the approximately 3,000 paramedics, emergency-service technicians, and fire-alarm dispatchers employed by the city under the collective-bargaining negotiations.

The ordinance exempts these workers from the agreement by classifying them alongside police, firefighters, sanitation employees, and correctional officers, which all get to pursue their own individual contracts. After the council overruled Mr. Giuliani’s veto of the ordinance, the mayor brought a lawsuit declaring it illegal. Lawyers for Mr. Bloomberg inherited the lawsuit and raised new separation of powers arguments on appeal, after a trial judge, Doris Ling-Cohan of state Supreme Court in Manhattan, ruled against the mayor in 2005.

Lawyers for Mr. Bloomberg promised to appeal yesterday’s decision to the state’s highest court.

“We are disappointed that the Appellate Division has upheld City Council provisions, which in our opinion improperly curtail the mayor’s power to bargain,” a lawyer for the city, Mordecai Newman, said in a statement sent via e-mail.

A lobbyist for the Local 2507 and the Fire Alarm Dispatcher’s Benevolent Association, Robert Ungar, said the decision was “helpful to our city’s first responders.”

Mr. Ungar said the Bloomberg administration has already met individually with the two unions this year to reach a contract.

The three judges who formed the majority are Eugene Nardelli, Luis Gonzalez, and James McGuire. The two dissenting judges are John Buckley and Milton Williams.