America's top judicial body will hear legal challenge questioning birthright citizenship.

The nation's highest court has decided to review a pivotal case that puts to the test a century-old guarantee: automatic citizenship for those born within US borders.

On his first day in office this winter, President Donald Trump enacted a directive aiming to end this practice, but the move was struck down by lower courts after constitutional questions were initiated.

The Supreme Court's eventual ruling will either support citizenship rights for the children of migrants who are in the US without authorization or on short-term permits, or it will nullify them entirely.

Next, the judges will calendar a session to hear the case between the administration and claimants, which include parents who are immigrants and their newborns.

The Legal Foundation

For over a century and a half, the 14th Amendment has codified the rule that all individuals born in the nation is a American citizen, with certain exclusions for children born to foreign diplomats and members of foreign military forces.

"Every individual born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States."

The challenged executive order sought to withhold citizenship to the offspring of people who are whether in the US in violation of immigration law or are in the country on short-term status.

The United States is among about a minority of states – primarily in the North and South America – that grant instant citizenship to all those born within their borders.