The U.S. International Trade Commission is scheduled to rule Friday afternoon whether aerospace giant Boeing was harmed by trade practices of Canadian competitor Bombardier.

The dispute stems from Bombardier's roughly 100-seat C Series jets, which Boeing complained to the U.S. government were sold to Delta Air Lines below cost of production and that the program received illegal subsidies from the Canadian government.

Last month, the U.S. Commerce Department upheld duties of nearly 300 percent on passenger jets made by Bombardier, a win for Boeing.

The decision had escalated the bitter trade dispute between the two aircraft manufacturers. It has also added to tensions between the U.S. and Canada, as the Trump administration seeks to renegotiate terms of the North American Free Trade Agreement, or NAFTA.

A four-member panel of the ITC, which investigates the effect of subsidies or dumping on the U.S. market, will make the determination, which is scheduled for 2:30 p.m. ET. If there is a tie, the decision will side with the petitioner, Boeing.

Bombardier had said the Commerce Department did not consider a common practice of airplane manufacturers: offering discounts to the first customers of new lines of aircraft.

Delta Air Lines in 2016 agreed to buy at least 75 planes from Bombardier.

In a twist, however, last October, European aerospace giant Airbus, Boeing's chief rival, said it would take a majority stake in the C Series program and said the planes could be manufactured in Alabama, where Airbus already makes narrowbody jets.

Delta CEO Ed Bastian has repeatedly said the airline won't pay the tariffs and called the duties "absurd."

The airline has not taken delivery of the C Series jets yet, so it has not been subjected to the tariffs. Delta, the second-largest U.S. airline, said it opted for the Bombardier jets because Boeing offered it no feasible alternative.