CSeries dumping petition by Boeing

On 28 April 2016, Bombardier Aerospace, a division of Bombardier Inc., recorded a firm order from Delta Air Lines for 75 CSeries CS100s plus 50 options. On 27 April 2017, The Boeing Company filed a petition for dumping them at $19.6m each, below their $33.2m production cost. On the same day, both Bombardier and the government of Canada rejected Boeing's claim, vowing to mount a "vigorous defence".

On 9 June 2017, the US International Trade Commission (USITC) found that the US industry could be threatened and should be protected. On 26 September, after lobbying by Boeing, the US Department of Commerce (DoC) alleged subsidies of 220% and intended to collect deposits accordingly, plus a preliminary 80% anti-dumping duty, resulting in a duty of 300%. The DoC announced its final ruling, a total duty of 292%, on 20 December, hailing it as an affirmation of the "America First" policy.

In October 2017, with financial issues already mounting, Bombardier was indirectly forced by the US government tariffs to relinquish 50.01% of its stake in the CSeries program to Airbus for a symbolic CAD$1, and would produce CSeries aircraft in the United States. The aircraft family was also subsequently renamed the Airbus A220.

On 10 January 2018, Canada formally filed a complaint at the World Trade Organization (WTO) against the United States over the affair. On 26 January, the four USITC commissioners unanimously reversed their earlier claims, finding that US industry is no longer threatened and no duty orders will be issued, overturning the imposed duties. The Commission public report was made available by February 2018. On March 22, Boeing declined to appeal the ruling. In 2020, amid mounting debts, Bombardier sold its remaining A220 stake to Airbus and exited the commercial plane business. With this deal, Airbus's stake in the A220 programme increased from 50.01% to 75%, while the Quebec government's holding rose to 25%, although it will not be injecting any new money into the program.