US Supreme Court will hear case disputing citizenship by birth.

The top court has agreed to take on a landmark case that puts to the test a century-old guarantee: automatic citizenship for people born within US borders.

On day one in office this January, the administration signed an order aiming to end the policy, but the action was subsequently blocked by lower courts after legal challenges were filed.

The Supreme Court's final ruling will ultimately support citizenship rights for the offspring of immigrants who are in the US illegally or on temporary visas, or it will nullify them entirely.

Next, the court will set a time to hear arguments between the government and plaintiffs, which comprise foreign-born parents and their infants.

A Constitutional Cornerstone

For nearly 160 years, the Fourteenth Amendment has codified the principle that all individuals born in the country is a US citizen, with certain exclusions for children born to foreign diplomats and personnel of invading forces.

"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 refuse citizenship to the children of people who are whether in the US without legal status or are in the country on short-term status.

The United States is among about 30 countries – largely in the Western Hemisphere – that provide immediate citizenship to any person born within their borders.