US Supreme Court will review legal challenge disputing automatic citizenship for those born in the US.

The nation's highest court has decided to review a pivotal case that puts to the test a longstanding constitutional right: birthright citizenship for individuals born within US borders.

On the inaugural day in office this January, President Donald Trump signed an order aiming to end this practice, but the order was subsequently blocked by lower courts after constitutional questions were brought forward.

The Supreme Court's final decision will either uphold citizenship rights for the offspring of foreign nationals who are in the US without authorization or on non-immigrant visas, or it will nullify them altogether.

Next, the court will set a time to hear the case between the administration and claimants, which comprise foreign-born parents and their infants.

A Constitutional Cornerstone

For over a century and a half, the Constitutional amendment has established the principle that anyone born in the nation is a citizen, with specific conditions for children born to foreign diplomats and members of occupying armies.

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

The contested directive sought to withhold citizenship to the children of people who are either in the US illegally or are in the country on short-term status.

The United States is one of about a minority of states – largely in the North and South America – that provide instant citizenship to any person born within their borders.