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

The US Supreme Court has will hear a landmark case that questions a longstanding principle: birthright citizenship for those born within US borders.

On his first day in office this winter, President Donald Trump signed an order aiming to end this practice, but the action was subsequently blocked by federal courts after legal challenges were brought forward.

The Supreme Court's final judgment will ultimately support citizenship rights for the infants of migrants who are in the US without authorization or on temporary visas, or it will overturn the provision entirely.

Next, the court will calendar a session to hear the case between the government and the suing parties, which comprise foreign-born parents and their young children.

The 14th Amendment

For over a century and a half, the Fourteenth Amendment has enshrined the doctrine that every person born in the United States is a citizen, with exceptions for children born to diplomats and personnel of occupying armies.

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

The disputed presidential order sought to withhold citizenship to the children of people who are either in the US without legal status or are in the country on non-permanent visas.

The United States belongs to a group of about three dozen nations – largely in the North and South America – that provide immediate citizenship to any person born on their soil.