President Donald Trump has falsely claimed the U.S. is alone in offering citizenship as a birthright. More than 30 countries do — but some have rolled it back.

President Trump's bid to cut off birthright citizenship is "flagrantly unlawful," attorneys for 18 states said in a lawsuit challenging the president's executive order.

The Democratic attorneys general and immigrant rights advocates say the question of birthright citizenship is settled law and that while presidents have broad authority, they are not kings.