A government investigation will continue into whether Canada's Bombardier is selling airliners in the U.S. at illegally subsidized prices, a claim that has raised trade tensions between the U.S. and Canada.
Chicago-based Boeing accuses Bombardier of violating antidumping and anti-subsidy laws by selling planes at below fair prices.
On Friday, the U.S. International Trade Commission voted 5-0 that there is enough evidence of harm to the U.S. aviation industry to let the Commerce Department go ahead with its investigation.
The Commerce Department is expected to have final decisions over the next four months. It could impose duties on Bombardier CSeries jets that hold 100 to 150 passengers.
Boeing argues that the new planes rely on illegal government subsidies, which allowed Bombardier to sell 75 jets to Atlanta-based Delta Air Lines at below-cost prices.
Bombardier said Friday that it was confident Boeing's claims will be rejected after more detailed review by U.S. officials.
Last month, Foreign Minister Chrystia Freeland warned that Canada could cancel a planned $2 billion purchase of 18 Boeing military jets over the dispute.
Boeing said "trade only works if everyone plays by the same rules," and it predicted that its business with Canada "will continue to thrive long after this commercial trade matter is resolved."