President Donald Trump’s executive order denying U.S. citizenship to the children of parents living in the country illegally has faced the first of what will be many legal tests.

A federal judge has temporarily blocked President Donald Trump’s executive order ending the constitutional guarantee of birthright citizenship regardless of the parents’ immigration status.

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,