On Wednesday, the U.S. Supreme Court heard one of the most socially charged questions of President Donald Trump’s second term: whether babies born in the U.S. are automatically citizens, even if their parents are not. 

The hearing focused on Trump’s January 20 executive order, which states that children born to parents who are in the country illegally or on temporary status should not automatically receive citizenship under the 14th Amendment. 

Lower courts have already struck down this policy, and now the justices are deciding whether to reverse more than a century of legal understanding that “all persons born or naturalized in the United States” are citizens.

Per CNN, during the two-hour session, justices questioned the administration’s lawyer, Solicitor General D. John Sauer, about how the framers of the 14th Amendment could have intended to exclude broad categories of children born on U.S. soil.

Chief Justice John Roberts expressed concern that the order could create “quirky” and “idiosyncratic” distinctions among infants based on their parents’ immigration status; Justice Amy Coney Barrett brought up questions about how the government would verify which babies qualify for citizenship at birth. 

Sauer claimed the policy targets “birth tourism” and relies on objectively verifiable immigration status. Though critics say low-income immigrant families would be impacted the most, and this could all lead to citizenship being stripped from hundreds of thousands of children each year.

Though it wasn't just the laws of the land being discussed. In a historic moment, President Trump sat in the courtroom for about 75 minutes, making him the first sitting president to attend live Supreme Court oral arguments. Despite the moment, the courtroom was unmoved.

“Though the president attending today’s arguments was a focus in the media, it was just business as usual in the courtroom,” said Grace Choi, a Skadden Fellow at ACLU Immigrants Rights Project, to CNN. “The real focus was on the legal arguments in this case as well as the ramifications that the order could have if it went into effect.”

The justices are expected to issue a ruling by June, which could redefine who is considered American-born in future generations.