Simply put, a Court where Justice William Brennan was the “swing vote” – which describes the Warren Court after Thurgood Marshall had replaced Justice Tom Clark in 1968 – isn’t really comparable to a Court where Justice Kennedy is the swing vote (for more on the methodological limitations of ideological measurements, see here and here). The issue matrixes have simply changed too much to meaningfully compare them. Or, to put it differently, if judicial liberalism is on the rise, it ain’t what it used to be.

For example, the Court in the late 1960s was probably prepared to declare shopping malls state actors subject to the First Amendment (compare here and here), to declare that the 14th Amendment applied to private action as well as state action (see here), and to allow busing across school district lines (see the vote breakdown here). One justice went so far as to personally enjoin the bombing of Cambodia (he was overruled in an opinion written by Marshall). I think some of these positions could fail to get a single vote on the present Court. It is hard to imagine the late Warren Court validating racial profiling in traffic stops, which the Rehnquist Court effectively did, unanimously, in 1996.

Moreover, plenty of today’s “liberal” decisions would have been considered downright reactionary in the 1960s (or 1970s). Consider the NFIB case, which upheld Obamacare in 2012, while finding that the individual mandate could not be supported by the commerce power. Until 1995, many scholars believed that the Commerce Clause had all but given Congress a general police power; the Lopez decision, which placed the first limits on congressional power in 60 years, was on the outer fringes of even conservative legal theory. NFIB actually reinforces, and to a certain extent expands that decision.