The National Labor Relations Board has accused Boeing of retaliating against its union workers by setting up a new non-union factory in South Carolina. The NLRB says in doing so, Boeing broke federal labor law.
The complaint has outraged some members of Congress, who have reacted by trying to cut funding for the NLRB.
The case has been a hot political topic for weeks, but on Tuesday the action moves into a Seattle courtroom. The NLRB is bringing the complaint before one of its own administrative law judges. Any appeals could eventually get to the federal courts.