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. It didn't fare well.

The 14th Amendment of the U.S. Constitution grants full citizenship to all persons "born or naturalized in the United States, and subject to the jurisdiction thereof."

A federal judge on Thursday temporarily blocked President Trump’s executive order to end automatic citizenship for babies born on American soil, dealing the president his first setback as he attempts to upend the nation’s immigration laws and reverse decades of precedent.

The ruling is an early setback for the new administration’s immigration agenda.

The ruling marks the first big loss for Trump, three days after taking the oath of office, and the temporary block applies to the entire country. U.S. District Judge John C. Coughenour called the order "blatantly unconstitutional.