A three-judge panel heard arguments Thursday on the Trump administration’s case for excluding undocumented immigrants from the 2020 census count, as an attorney for the New York attorney general’s office argued that the move was a blatant violation of the U.S. Constitution.

The hearing came amid a lawsuit by a New York state-led coalition of states, cities and immigrant-advocacy groups seeking to halt President Donald Trump’s July 21 order directing the U.S. Commerce Department not to include unauthorized immigrants in the constitutionally mandated head count of all persons residing in the country.