Immigration activists rally outside the Supreme Court as the justices hear arguments over the Trump administration’s plan to ask about citizenship on the 2020 census, in Washington, Tuesday. Photo: Diego M. Radzinschi/ALM

The Trump administration’s plan to include a citizenship question on the 2020 census encountered some skepticism Tuesday from the U.S. Supreme Court as the justices probed the reasons why the U.S. Commerce Department added the question and its potential impact on the census’s accuracy.