The U.S. International Trade Commission will deliver its decision on whether domestic solar panel manufacturers have been injured by a surge in imports Friday morning, in what could be the first step toward President Donald Trump curbing trade in a multibillion-dollar industry.

However the commission rules, the trade case will be remarkable for the involvement of one law firm, Mayer Brown, which is now representing bankrupt U.S. solar company Suniva after years of fighting on behalf of Chinese and other foreign firms in similar proceedings.

In the arena of international trade law, where attorneys duke it out before quasi-judicial administrative agencies like the USITC and the Commerce Department over whether to slap tariffs on “unfair” imports, switching sides is unusual—if not unheard of. Firms usually either represent petitioning U.S. companies, or foreign exporter respondents, but rarely both.