An appeals court in New York dismissed the state attorney general’s lawsuit against Amazon over its coronavirus safety protocols and a former employee who led the successful union organizing effort on Staten Island.

Besides potentially exposing workers to the virus at two Amazon facilities at New York City, the lawsuit filed by Letitia James last year claimed that Amazon illegally retaliated against workers who spoke up about poor safety conditions in its warehouses. They include the fired Amazon worker who now heads the Amazon Labor Union, Christian Smalls, and the group’s vice president of organizing, Derrick Palmer.

The appellate court said in its ruling Tuesday that federal labor law preempted state labor law, and the National Labor Relations Board “should serve as the forum” for disputes arising from conduct that’s protected or prohibited by federal labor law, not the states.

It also said the lawsuit’s efforts to require the retailer to comply with New York’s Covid workplace guidelines was dismissed as moot because the restriction in place at the time have since been lifted.

The court also pointed to a separate NLRB case over another fired employee, Gerald Bryson. It said that case involves “essentially the same allegations of retaliation, and the possibility of inconsistent rulings on the same issue poses an ‘obvious and substantial’ ‘risk of interference” with the NLRB’s jurisdiction.

Mr. Palmer, who was given a final written warning in the early days of the pandemic, is still employed at Amazon.

The court’s ruling is a win for Amazon which had sought to have the case thrown out. Neither Amazon, nor Ms. James’s office immediately responded to a request for comment.