The lawsuits against the new Trump administration have begun.

Maryland Attorney General Anthony Brown announced Tuesday that he was joining 22 other states to challenge President Donald Trump’s executive order ending birthright citizenship — the constitutional guarantee of citizenship to anyone born on U.S. soil.

Trump’s order, which came amid a flurry of executive actions he took on his first day back in office, claims the Constitution does not extend birthright citizenship to all children born here regardless of their parents’ legal status, though that has been U.S. policy for decades. The order received swift backlash and is expected to face significant legal hurdles.

“Birthright citizenship is a right enshrined in our Constitution,” Brown said in a news release. “It is a reflection of our country’s ideals, a belief that every baby born on U.S. soil is a member of our great nation and deserves to play a part in its future. Ending birthright citizenship is un-American, and our office will vigorously challenge this blatantly unconstitutional decision in court.”

The states filed their lawsuit in U.S. District Court in Massachusetts. The complaint seeks an order blocking enforcement of the administrative order, which is scheduled to take effect on Feb. 19.

Brown’s office said in a news release that children who are born in the U.S. but denied citizenship will lose a chance to fully participate in American society — they will not be able to obtain Social Security numbers, vote or work lawfully. The lawsuit also claims the executive order will harm states by cutting federal funding for programs they administer that depend, at least in part, on the immigration status of the person receiving services.

The White House said it’s ready to face the states in court and called the lawsuits “nothing more than an extension of the Left’s resistance.”

“Radical Leftists can either choose to swim against the tide and reject the overwhelming will of the people, or they can get on board and work with President Trump,” White House deputy press secretary Harrison Fields said.

The 14th Amendment states that, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.”

The Trump administration has adopted a strict — and many legal observers say inaccurate — reading of the amendment, arguing that the phrase “subject to the jurisdiction thereof” means that U.S. citizenship does not automatically extend to people whose mother was unlawfully in the U.S. when they were born and whose father was not a citizen or permanent resident; or to people whose mother was in the county legally but temporarily, such as on a student visa, and whose father was not a citizen or permanent resident.

The 14th Amendment did not always guarantee birthright citizenship to all U.S.-born people.

In 1898 an important birthright citizenship case unfolded in the U.S. Supreme Court. The court held that Wong Kim Ark, who was born in San Francisco to Chinese immigrants, was a U.S. citizen because he was born in the country. After a trip abroad, he had faced denied reentry by the federal government on the grounds that he wasn’t a citizen under the Chinese Exclusion Act.

But some advocates of immigration restrictions have argued that while the case clearly applied to children born to parents who are both legal immigrants, it’s less clear whether it applies to children born to parents without legal status.

Others joining Maryland in the suit are California, Colorado, Connecticut, Delaware, Hawaii, Maine, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Rhode Island, Vermont, and Wisconsin and the cities of Washington, D.C. and San Francisco. Arizona, Illinois, Oregon and Washington filed a separate suit.

The Associated Press contributed to this story.