The part of the 14th Amendment that is debated is the statement in section 1 shown below.
Amendment XIV
Section 1.
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.
Those who favor citizenship for children born on U.S. soil to an illegal immigrant mother will say that the baby is a subject to the jurisdiction of the U.S., meaning they are subjected to the laws of the U.S.. And therefore they are U.S. citizens in accordance with the Constitution as written.
However, when you look at original intent at the time the amendment was written and ratified (1868), no one could have expected mass illegal immigration into the U.S. for the sole purpose of having a child on U.S. soil so the child would become a U.S. citizen.
There were no social welfare programs and no education and healthcare systems in place so the authors of the amendment could not foresee the possible anchor baby issue.
If the originators of the 14th Amendment could have foreseen the anchor baby issue I am certain they would have added clarification to the amendment in order to protect U.S. taxpayers from having to pay for the children of illegal immigrants, people who violate U.S. immigration laws to enter the U.S..
After the Civil War some people argued that freed slaves were not citizens, because they didn’t enjoy citizenship as slaves. The first part of the 14th was written to grant citizenship to slaves. Unlike illegal aliens slaves were “subject to the jurisdiction” of the United States government.