On Monday, police fired tear gas at peaceful protesters so that President Donald Trump could pose for a photo. Trump was condemned widely—even by former Defense Secretary James Mattis. Now, he’s being sued. The ACLU of DC, on behalf of the DC chapter of Black Lives Matter and individual protesters who were attacked in the president’s stunt, filed a lawsuit on Thursday against Trump, attorney general William Barr, and other federal officials for violating their constitutional rights.