The union representing the Dartmouth men’s basketball team filed an unfair labor practice charge against the Ivy League school on Wednesday because it has refused to negotiate with the players on a collective bargaining agreement.

Service Employees International Union Local 560, which already represents some other workers at the Hanover, New Hampshire, school, said the failure to bargain was a violation of both labor law and the school’s own code of ethics.

“For nearly 60 years, Dartmouth has followed a tradition of bargaining fair and equitable union contracts with our local,” union president Chris Peck said in a statement. “It is past time for Dartmouth administration to avoid the looming financial and legal liabilities by grasping this opportunity to show leadership, as the players have, and live up to its own rhetoric regarding the importance of both community and dialogue.”

A regional director of the National Labor Relations Board ruled in March that Dartmouth men’s basketball players were employees of the school, clearing the way for them to unionize. The players then voted 13-2 to join SEIU Local 560.

Dartmouth responded by announcing that it would not bargain with the players — a tactic designed to force the case into court in the hopes that a federal judge would overturn the NLRB decision.

“While we continue to negotiate in good faith with multiple unions representing Dartmouth employees, our responsibility to future generations of students means we must explore all our legal options for challenging the regional director’s error — which was contrary to every legal precedent,” the school said in a statement on Wednesday.

Refusing to bargain with the players “is an unprecedented step in Dartmouth’s long history of labor negotiations, but it is the only lever we can engage to ensure this matter is reviewed by a federal court,” the school said. “We expected this action would result in their filing an unfair labor practice charge with the NLRB, which they did and which we will also appeal.”

NLRB regional director Laura Sacks ruled in March that Dartmouth held enough control over the men’s basketball players that they were legally employees of the school entitled to collectively bargain over working conditions like practice hours and travel, as well as salary. Although the decision applies only to the men’s basketball team at Dartmouth, which sought to unionize, the players have said they hope other teams on campus or at other schools will follow their example.

Dartmouth has asked for a review of the regional director’s decision by the full board.

“Dartmouth’s decades-long commitment to athletics is an extension of our academic mission, and we maintain that the regional director made an extraordinary mistake in finding these students are employees,” the school said on Wednesday. “Varsity athletes in the Ivy League are not employees; they are students whose educational program includes athletics. The Ivy League was formed in 1954 with a commitment to the primacy of academics, which was visionary at the time and even more so today.”