In the decision obtained by the Daily Times, the Labor Management Relations Board concluded that the Aztec Education Association had failed to negotiate in good faith with the district.
The labor board said the union had submitted proposals in conflict with state statutes and the New Mexico Constitution, and it failed to follow rules agreed upon by both parties before negotiations.
The complaint was filed on Sept. 13 by the school district against the union. The union is composed of all certified employees working for the district, except administrators.
More than 200 employees are part of the union, Superintendent Kirk Carpenter said, including teachers, counselors, social workers and nurses.
Carpenter said he wasn't happy with having to file the complaint in the first place but was eager to move forward with negotiations.
"It's one of those things you don't feel good about. You don't want to get to this point," Carpenter said. "Not a situation where you are happy to say, Hey, we won,' but we look to move forward."
Roxie De Santiago, a Santa Fe-based attorney representing the union, would not discuss her side's next step.
"We need time to look at the written decision and decide how to precede," De Santiago said.
The labor board ended its conclusions with a statement saying the parties should work together in good faith bargaining that follows the rules.