Boeing filed ta petition with the USITC, but it was ultimately the Department of Commerce that fined them for what they decided was unfair trade.

The USITC reversed their own decision a year or so later, and Boeing chose to not appeal the decision, but Bombardier and Canada ended up deciding to not pursue things further.

Bombardier had a lot of other problems going on as well. Generally, their entire transportation division (they also had railcar manufacturing) had manufacturing and timeline issues. The price cut that resulted in the dumping penalties was an attempt to shore up a program that was already flailing.

You mean to say the rights were sold to Airbus, who went on to acquire more.