A federal judge Thursday blocked President Donald Trump’s executive order outlawing birthright citizenship—the policy automatically giving citizenship to anyone born in the U.S.—and declared it “blatantly unconstitutional,

Put simply, under Trump’s order, the children of most undocumented immigrants wouldn’t be US citizens, nor would the children of people in the country on student, work, or tourist visas. This is more than a reinterpretation of the 14th Amendment — it’s an attempt to do away with the jus soli principle that undergirds US citizenship.