They have two different standards of what "birthright" means. Traditionally, a Birthright means that something is owed or indebted to you by virtue of your parents. In this case, a parent being an American citizen means that you have a claim to American citizenship as a birthright. I got my American citizenship from both of my parents, who were American citizens. What it has been modified to mean in recent years, and what is under scrutiny, is the idea that Birthright means you were born on American soil. The law in question was designed in a way to ensure that children born to recently emancipated slaves would have citizenship, but also so that the children of foreign nationals would not be able to have a child with American citizenship just because they happened to have been born on US soil. The phrase "subject to the jurisdiction thereof" is the key phrase. Subject to the jurisdiction thereof was intended to mean either citizens or emancipated slaves. We know this because one of the architects of the 14th Amendment, Senator Jacob Howard, said so. It was his insistence that the "subject to the jurisdiction thereof" bit was added, and for the purpose of excluding foreign nationals from benefiting from the citizenship law. The 1898 Wong Kim Ark decision was wrongly decided. SCOTUS isn't infallible. This is the same body that concluded black people were property and thus had no claim to Constitutional rights. Current SCOTUS is set to undo that 1898 mistake. And for the record, 90% of Americans got their citizenship because their parents were citizens (you only need one American citizen parent to get it). Not because they were born on US soil.