In its ruling, the three-member WTO panel does not agree with all of China’s complaints about the US investigation and its judgments.

But the WTO concludes that in some instances the US overstepped its legal boundaries, and says the US should “bring its measures into conformity with its obligations” under agreed trade law.

The Coalition for Affordable Solar Energy (CASE), the lobbying group established to oppose SolarWorld's push for tariffs on Chinese cells and modules, quickly trumpeted its support for the decision.

"Today’s