America's top judicial body agrees to hear lawsuit challenging birthright citizenship.

The top court has will hear a significant case that puts to the test a longstanding constitutional right: automatic citizenship for people born within US borders.

On his first day in office this January, President Donald Trump enacted a directive aiming to terminate the policy, but the move was subsequently blocked by the judiciary after constitutional questions were filed.

The Supreme Court's eventual judgment will ultimately uphold citizenship rights for the infants of migrants who are in the US undocumented or on temporary visas, or it will end the provision completely.

Next, the court will set a time to hear oral arguments between the federal government and the suing parties, which comprise immigrant parents and their young children.

The 14th Amendment

For over a century and a half, the 14th Amendment has enshrined the rule that all individuals born in the country is a US citizen, with exceptions for children born to foreign diplomats and personnel of invading forces.

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

The disputed directive sought to refuse citizenship to the children of people who are either in the US illegally or are in the country on non-permanent visas.

The United States is one of about 30 countries – largely in the North and South America – that award instant citizenship to any person born on their soil.