The Knight First Amendment Institute, which has led a legal fight against Trump for blocking critics on Twitter, has officially asked Rep. Alexandria Ocasio-Cortez (D-NY) to stop similar practices. The institute sent a letter to Ocasio-Cortez’s office late yesterday, urging her to unblock anybody who was targeted “because of the viewpoints they have expressed,” while also acknowledging that some blocks might be “both reasonable and constitutionally legitimate.”

Multiple US courts have ruled that government social media accounts can be constitutionally protected public spaces, including the Twitter account of President Donald Trump whom the Knight Institute sued for blocking accounts for political reasons in 2017. The Second Circuit Court of Appeals affirmed this decision last month.

Within days, three people sued Ocasio-Cortez for blocking them: former New York assemblyman Dov Hikind, Staten Island congressional candidate Joseph Saladino, and self-described “Jewish journalist” Harry Cherry. Saladino called his suit a “social experiment” to see if courts would apply the same legal standards to a conservative president and a liberal congresswoman.

Ocasio-Cortez has responded to Hikind’s complaint denying that he was blocked for expressing opinions and denying that she uses her popular @AOC Twitter account as a public forum. The Knight Institute took issue with the claim. “You use the account as an extension of your office — to share information about congressional hearings, to explain policy proposals, to advocate legislation, and to solicit public comment about issues relating to government,” reads its letter.

But the institute says that some tweets, like those including threats, wouldn’t be protected political speech. Ocasio-Cortez also faces high levels of racist and sexist abuse on social media, and the institute acknowledges that having to deal with harassment can paradoxically deter people from participating in the democratic process. Legal scholars noted that last month’s ruling raised complicated questions about dealing with harassment, especially in venues outside Twitter where moderation involves actually removing comments and not just blocking users.

Consequently, the Knight Institute has suggested that it work with Ocasio-Cortez to develop a social media policy that “both complies with the First Amendment and helps you address threats, abuse, and harassment.” It’s publicly expressed concerns with her blocking tactics, but now, it’s directly addressing the congresswoman herself and bringing attention to an ongoing legal battle.