A third federal court has put the brakes on the Trump administration's plans to add a citizenship question to the 2020 Census.

U.S. District Court Judge George Hazel in Maryland on Friday determined the Trump administration's addition of the question, "Is this person a citizen of the United States?" is a violation of federal administrative law, favoring the plaintiffs in the lawsuit.

"Based on the foregoing, the court will enter judgment for the plaintiffs, enjoining defendants from including the citizenship question on the 2020 Census," the judge's opinion reads.

Get Breaking News Delivered to Your Inbox

Federal judges in New York and California had already come to similar conclusions. The Supreme Court is expected to about the constitutionality of the question on April 23.

The question, added by Commerce Secretary Wilbur Ross, has become a point of contention both in the courts and in Congress, where House Democrats have hammered the administration. Critics of adding the question worry it will make undocumented immigrants fearful of answering and provide inaccurate population estimates, while proponents of the question insist it's necessary to provide an accurate number of immigrants in the country illegally. The president has insisted there are as many as 30 million illegal immigrants in the U.S., although other estimates are lower.

Mr. Trump has called some Democrats "radical" for not wanting to include the question.

"Can you believe that the Radical Left Democrats want to do our new and very important Census Report without the all important Citizenship Question," he tweeted on April Fool's Day. "Report would be meaningless and a waste of the $Billions (ridiculous) that it costs to put together!"

Ross testified about the citizenship question before Congress last month. Ross claimed he didn't believe he discussed the question with the White House before adding it. "Not that I can recall," the secretary told lawmakers on Capitol Hill last month.

Mr. Trump is at the border in California Friday as he continues his threats to close parts or all of the southern border with Mexico, if the country doesn't stop the flow of illegal immigrants into the U.S.