The independent, bipartisan trade organization voted unanimously against duties imposed by the U.S. Commerce Department in October.
The firm said it will be reviewing the the Commission's more detailed opinions in the coming days, and will continue to document any perceived harm to its business and its USA supply chain from what it defines as "illegal subsidies".
"The U.S. values its relationships with Canada, but even our closest allies must play by the rules", Commerce Secretary Wilbur Ross said in announcing the plans to seek triple-digit duties in the case.
It also alienated top customer Delta Air Lines, blocked from buying the CSeries by the proposed tariffs.
Boeing Co (BA.N), the world's largest maker of jetliners, accuses the Canadian firm of dumping planes on the USA market.
"The ruling confirms the right of the Canadian and Quebec governments to engage in industrial policy to safeguard jobs and support high tech innovation", said Renaud Gagné, Unifor Quebec Director.
Trump able to apologise for far-right video retweets
Trump said "I don't want to cause any difficulty for your country" when Morgan pressed him on whether he would apologize. Sanders also stated that Trump didn't verify facts in the videos before sharing them.
It alone is responsible for the design, manufacture and assembly of the advanced composite wings for every CSeries aircraft. In its deposition during the ITC proceedings, Delta simply said that Boeing did not offer anything that was considered viable by the company.
"Boeing's claims of threatened injury - premised on a false depiction of Boeing as David to Bombardier's Goliath - are convoluted, misleading, and/or speculative", Bombardier said in its final comments.
"This was always a stretch in terms of Boeing's claims", said Alden.
Before that, Bombardier had struggled to gain a USA foothold while production of the single-aisle plane fell more than two years behind schedule and costs ballooned to more than US$2 billion over budget.
It's a victory for Canada as well as Bombardier and should "put some wind in the sails" of current NAFTA negotiations, said Karl Moore, an associate professor of the Desautels Faculty of Management at McGill University in Montreal.
"This ruling is testament to the unwavering campaign by all involved in exposing the complaint from Boeing for what it really was - a bid to silence a competitor". Boeing is in talks about a potential combination with the Canadian company's top rival, Embraer SA, which sells planes that directly compete with the CSeries.
"This whole Bombardier saga must act as a warning to the UK Government about the kind of battles it faces to defend UK jobs and industries as we leave the European Union and face the increasingly hostile territory of trade wars on our own".
"Today is a huge victory for one of Canada's most important industries and as a Bombardier employee I'm absolutely thrilled and dumbfounded that this decision actually came down".