The World Trade Organisation (WTO) has overturned a ruling that Boeing received prohibited support for its newest aircraft, the 777X, in a blow to the European Union and rival Airbus.
The EU has been embroiled in a dispute with the US for more than a decade over aerospace subsidies.
The WTO appellate body's decision reverses a ruling from last year that found a tax incentive for the production of the Boeing 777X jet in Washington state had deliberately shut out imports. The appeals body said the tax breaks had not explicitly targeted trade flows.
"The WTO has rejected yet another of the baseless claims the EU has made as it attempts to divert attention from the $22bn of subsidies European governments have provided to Airbus and that the WTO has found to be illegal," said Boeing general counsel J. Michael Luttig.
"No further appeal of today's decision is available to the EU," he added, calling the decision a "sweeping and clean win" for the US.
However, Airbus said it wasn't finished yet.
"Boeing illegal subsidies are still illegal and need to be removed," said Rainer Ohler, Airbus executive vice president of communications.
“The 'game' is far from over.”