Trump’s executive order, signed in January, seeks to deny citizenship to children who are born to people who are living in the U.S. illegally or temporarily. It is part of the hard-line immigration agenda of the president, who has called birthright citizenship a “magnet for illegal immigration.”

Even if the mothers' immigration statuses were called into question and even if Trump was not married to them at the time of the children's births, all of Trump's children have an American father. Thus, Trump's executive order against birthright citizenship would not affect the statuses of his own children.

In last month’s decision limiting one judicial tool, universal injunctions, the court seemed to invite lower courts to use class actions as an alternative.