The Center for Democracy and Technology has sued President Donald Trump over an executive order seeking to crack down on social media companies’ “selective censorship” after Twitter flagged one of the president’s posts as potentially misleading.

Mayer Brown is representing the Washington, D.C.-based tech policy nonprofit in one of the first legal challenges to the executive order delegating several agencies to review Section 230, a provision within the Communications Decency Act shielding online companies from liability for user-generated content.