Critics of birthright citizenship focus on Wong Kim Ark as if it were the source of the doctrine. They are eager to find a hole—any hole—in its holding. Hence the claim that the case reserved the issue of children of “those who are here illegally.”

Politifact investigated Paul’s claim about Wong Kim Ark late last week, and rated it “Mostly True.” And it is true, in the following sense. In Wong Kim Ark, the Court said that Wong, an adult-male child of Chinese immigrants legally present, was a citizen. It didn’t specifically state that an adult-male child of, say, Mexican immigrants legally present was a citizen. It did not state that an adult female child of immigrants lawfully present was a citizen. It did not state that a gay or lesbian child of immigrants was a citizen. It also didn’t discuss whether a small gray alien in a disk-shaped spacecraft would have citizen children. It said nothing about “green cards,” which didn’t exist. It did say this:

The Fourteenth Amendment affirms the ancient and fundamental rule of citizenship by birth within the territory, in the allegiance and under the protection of the country, including all children here born of resident aliens, with the exceptions or qualifications (as old as the rule itself) of children of foreign sovereigns or their ministers, or born on foreign public ships, or of enemies within and during a hostile occupation of part of our territory, and with the single additional exception of children of members of the Indian tribes owing direct allegiance to their several tribes.

It’s pretty emphatic. If there were another exception, it seems to me, the Court would not have held it back.

In 1898, even the idea of “illegal immigration” barely existed. Chinese immigration had been halted in 1882, and Chinese present in the U.S. had to carry papers. Japanese and Korean immigrants, however, could still enter freely; they would face similar racial restrictions in the 20th Century. The border with Mexico was wide open by design, and Latino people in the Southwest moved back and forth freely. On the east coast, the doors were open wide. In her book, Impossible Subjects: Illegal Aliens and the Making of America, the Columbia University historian Mae Ngai relates that the concept of “illegal presence” did not come to the fore in the law until after the passage of the Johnson-Reed Act of 1924. Paul’s statement is “mostly true” because it’s something the justices would not even have thought to discuss.

The term “illegal immigrant,” according to the Oxford English Dictionary, originated in the late 1930s to mean “a Jew who entered or attempted to enter Palestine without official permission during the later years of the British mandate. “Illegal alien” appears somewhat later; the earliest use I can find is in 1950, when a federal appeals court used it to describe a Polish-born Mexican citizen whom Immigration and Naturalization Service officers had arrested while he was attempting to swim back across the Rio Grande: “the United States would have been quickly and cheaply relieved of an illegal alien, had appellant swum the river that night according to plan.” (It pops up again a few years later in a Stanford Law Review article engagingly titled “Wetbacks: Can the States Curb Illegal Entry?”)