U.S. President Donald Trump has said he is planning to sign an executive order ending birthright citizenship of the United States – i.e., the automatic conferral of citizenship on any individual born in the U.S.

"We're the only country in the world where a person comes in, has a baby, and the baby is essentially a citizen of the United States for 85 years with all of those benefits," Mr Trump said to ‘Axios on HBO’, a documentary series, clips of which have been released. "It's ridiculous. It's ridiculous. And it has to end,” he said.

It is factually incorrect that the U.S. is the only country in the world with birthright citizenship laws, although only a minority have such laws.

Mr. Trump said he has consulted his counsel on this and plans to proceed with the executive order, which is almost certain to face legal challenges – as have his executive orders banning the entry into the U.S. of citizens from certain Muslim majority countries. It is by no means clear that the president has the legal authority to effect such a broad legal change through an executive order.

The concept of jus soli (‘right of the soil’) derives from the 14 Amendment to the U.S. Constitution, enacted in 1868 after the Civil War, in order to grant legal rights to former slaves. It says, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the state wherein they reside.”

Therefore, individuals born in the U.S., to parents on temporary visas or here without a valid visa are also U.S. citizens. This has been central to motivating Republicans who want to end birthright citizenship. The US Department of Homeland Security put the number of foreigners without legal status in the U.S. at a little above 12 million in 2014.

Mr. Trump has been talking tough on borders, security and immigration, highly divisive topics in the U.S. these days, in the run up to November 6 midterm elections.