How did it come about, for example, that illegal aliens gained a right to social-welfare benefits? We learn from Levin that in the early 20th century, the Court took for granted that citizens could be preferred over noncitizens in many different contexts. Thus, in 1915 it upheld New York's right to reserve transit-authority jobs for citizens, while in 1927 it specifically rejected the proposition that the Fourteenth Amendment's equal-protection clause applied to aliens.
But in the civil-rights revolution of the 1960's and 70's, powerfully abetted by the Warren and Burger Courts, this logic fell off the table. A decision written in 1971 by Justice Blackmun held that "classifications based on alienage, like those based on nationality or race, are inherently suspect and subject to close judicial scrutiny""a standard, often impossible to meet, requiring legislators to demonstrate a "compelling government interest" in any rules disadvantaging aliens. n 1976, the Court held unanimously that it was unconstitutional for the federal government to bar aliens from civil service jobs. In a critical 5-4 decision written by Justice Brennan in 1982, it held that Texas could not bar the children of illegal aliens from its public schools. The decision was based on the equal-protection clause, which meant that it also applied to social benefits for all aliens (including the illegals).
This is why Linda Chavez, for example, could say she opposed Prop. 187 because it was it was "unconstitutional."