BOSTON (CBS) –NHL Commissioner Gary Bettman has upheld Shawn Thornton’s 15-game suspension, the league announced on Tuesday.

Thornton can now serve the rest of the suspension, or bring the case to a neutral arbitrator. He has seven days to make that decision.

Read: Bettman’s Explanation

“Simply put, this was a bad act with a bad result, and neither will be tolerated in our game,” Bettman wrote in his explanation. “Again, I note that Mr. Thornton has a reputation for being a ‘good actor’ and a model NHL citizen, but that does not eliminate the need for him to be punished appropriately for his bad act in this case.”

The Bruins released the following statement regarding Bettman’s decision:

“We respect the process including the ability to attend the hearing with Commissioner Bettman in support of Shawn. At this time, we will decline comment until the process is complete and Shawn has exhausted all rights available to him.”

Thornton was suspended on December 14, one week after he skated behind Brooks Orpik in a scrum, took the Penguins defenseman down to the ice and delivered a series of punches that left Orpik unconscious on the TD Garden ice. Orpik was removed from the ice on a stretcher and was diagnosed with a concussion.

Thornton decided to appeal the suspension and had an in-person hearing with Bettman last Friday.

Thornton has already sat out eight games since the incident and is eligible to return January 11 against San Jose. The 15-game suspension will take more than $84,000 off Thornton’s salary of $1.1 million. Those funds will be donated to the Players’ Emergency Assistance Fund.

Since Brendan Shanahan took over as the NHL’s chief disciplinarian in 2011, the 15-game suspension is the longest he’s given to any player in the regular season. Raffi Torres was suspended for 25 games during the 2012 playoffs for hitting Marian Hossa in the head, though that penalty was reduced to 21 games after Torres appealed the ruling.

Previously, Shanahan’s longest regular-season suspension was for 10 games. Patrick Kaleta was issued a 10-game ban earlier this year. He also appealed the decision, though it was upheld by Bettman. Kaleta opted to not send the appeal to an independent arbitrator.