The NHL on Wednesday filed a lawsuit against its players union, seeking to restore a 20-game suspension against Calgary Flames defenseman Dennis Wideman that a ¡°neutral¡± arbitrator later cut in half.

In a complaint filed in the U.S. District Court in Manhattan, the NHL said arbitrator James Oldham ¡°applied his own brand of industrial justice¡± by ignoring the findings of commissioner Gary Bettman, who upheld the original suspension, and substituting a shorter 10-game ban.

A lawyer for the NHL Players¡¯ Association had no immediate comment. Oldham did not immediately respond to a request for comment.

Wideman was suspended for cross-checking NHL linesman Don Henderson from behind with his stick during a Jan. 27, 2016, game with the Nashville Predators.

According to the league, the blow caused Henderson to fall face first onto the ice, leaving him with a concussion and unable to resume work as a linesman.

The players¡¯ union appealed the 20-game ban to Oldham, a Georgetown University law professor, as permitted under its collective bargaining agreement (CBA).

But the NHL said Oldham did not act as a ¡°neutral discipline arbitrator¡± (NDA) in halving Wideman¡¯s ban, given the lack of ¡°substantial evidence¡± that Bettman¡¯s decision was wrong.

¡°The NDA exceeded his authority under the CBA and applied his own brand of industrial justice by disregarding the standard of review set forth in the CBA,¡± the complaint said.