The Alien Enemies Act of 1798 gives the president wartime powers to deport undocumented immigrants with little to no due process.

US District Judge James Boasberg vowed on Friday to find out whether officials in the Trump administration violated his orders temporarily blocking the use of an 1798 law for deportations by refusing to turn two flights around last weekend.

Judge James Boasberg started off the hearing by telling Deputy Assistant Attorney General Drew Ensign that, in filings over the course of this week, there had been “disrespectful, intemperate language” of a sort he had “never seen from the United States.”