This area of law is complicated, but the answer is: a little of each. The usual strategy is to circumvent sovereign immunity through a nifty legal trick: sue a

This area of law is complicated, but the answer is: a little of each. The usual strategy is to circumvent sovereign immunity through a nifty legal trick: sue agents of the government in their individual capacity. https://www.law.cornell.edu/wex/bivens_actions https://www.law.cornell.edu/wex/bivens_actions That appears to be what they did here. Note that the first defendant is Donald Trump, not the United States. (This presents its own set of challenges, that I'm glossing over here. But this is the general approach.) There are also statutes waiving sovereign immunity in a number of cases. The Federal Torts Claims Act is the big one. https://www.law.cornell.edu/uscode/text/28/2674 https://www.law.cornell.edu/uscode/text/28/2674