Columbia Law School’s Knight First Amendment Institute is asking President Donald Trump to unblock people on Twitter — and threatening him with legal action if he doesn’t comply.

Trump, like many other Twitter users, routinely blocks critics, trolls, and other ne’er-do-wells from following him on the social media platform. But, as president of the United States, Trump is not like any other Twitter users.

The Knight Institute decided to let Trump know in a letter written on behalf of individuals who have been blocked that he could be running afoul of the Constitution.

“We write on behalf of individuals who have been blocked from your most-followed Twitter account, @realDonaldTrump, because they disagreed with, criticized, or mocked you or your actions as president,” the Knight Institute letter reads. “This Twitter account operates as a ‘designated public forum’ for First Amendment purposes, and accordingly the viewpoint-based blocking of our clients is unconstitutional. We ask that you unblock them and any others who have been blocked for similar reasons.”

Several users are cited, including Holly O’Reilly, who goes by the Twitter handle @AynRandPaulRyan. She was blocked after the following Tweet:

The letter complains that the blocking violates the First Amendment because Trump’s account “constitutes a designated public forum,” much like White House press briefings or a city council meeting.

Still, the letter wasn’t all criticisms: The Knight Institute praised the president for his use of the social medium to communicate with the public.

“Your vigorous use of Twitter to comment about matters mundane as well as momentous has afforded Americans valuable insight into your policies, actions, and beliefs,” the letter said. “It has also supplied the public with a means of engaging you directly.”

The Knight Institute is just trying to make sure all American Twitter users have the chance to share their thoughts with the president.

Top photo: President Donald Trump heads to the Oval Office after speaking in the Rose Garden of the White House on June 1, 2017.