Tesla and SpaceX -- two companies owned by Elon Musk -- have signed on to a legal brief in support of a lawsuit against President Trump’s executive order on immigration and refugees.

Musk has been on the defensive for the past week for remaining a member of the president’s advisory councils in the wake of the executive order, which drew the ire of Silicon Valley.

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Late on Sunday, 97 companies, mostly from the tech world, filed an amicus brief in support of a lawsuit brought by Washington State against the executive order that temporarily blocks entry to the U.S. of refugees and citizens from seven mostly Muslim countries.

Musk’s companies, Tesla and SpaceX, were conspicuously absent from the filing, but on Monday night they joined 29 additional companies that signed on to the brief.

“As soon we saw the brief this morning, we insisted on being added,” a Tesla spokesperson told The Hill.

Musk has had to defend his involvement with Trump’s business advisory council in the wake of the ban being implemented, especially after Uber CEO Travis Kalanick stepped down from the panel after his consumers began boycotting his app.

“Activists should be pushing for more moderates to advise President, not fewer. How could having only extremists advise him possibly be good?” Musk tweeted on Sunday.