America's top judicial body agrees to consider case questioning citizenship by birth.

The US Supreme Court has agreed to take on a landmark case that questions a longstanding guarantee: birthright citizenship for people born on American soil.

On his first day in office this winter, the President issued an executive order aiming to halt this practice, but the action was subsequently blocked by lower courts after constitutional questions were brought forward.

The Supreme Court's eventual judgment will either support citizenship rights for the infants of migrants who are in the US without authorization or on temporary visas, or it will nullify the provision completely.

Next, the judges will calendar a session to hear arguments between the government and plaintiffs, which involve parents who are immigrants and their infants.

A Constitutional Cornerstone

For nearly 160 years, the Fourteenth Amendment has codified the principle that every person born in the United States is a 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 directive sought to withhold citizenship to the offspring of people who are either in the US without legal status or are in the country on non-permanent visas.

The United States is one of about three dozen nations – largely in the North and South America – that grant instant citizenship to all those born in their territory.