"Birth on U.S. territory has never been an absolute claim to citizenship"

This quote by Phyllis Schlafly is describing the concept of birthright citizenship, which is the concept that any person born in the United States is immediately a citizen of the nation. Schlafly is recommending that this is not always the case, which being born upon U.S. area does not ensure citizenship. This is since the U.S. Constitution does not clearly state that birth on U.S. soil immediately grants citizenship. Instead, the 14th Amendment states that "all persons born or naturalized in the United States, and based on the jurisdiction thereof, are people of the United States." This suggests that there are certain conditions that should be fulfilled in order for a person to be approved citizenship, such as going through the jurisdiction of the United States. Therefore, Schlafly is suggesting that birth on U.S. territory is not an absolute claim to citizenship, which other aspects need to be taken into account.