One thing pundits should keep in mind about court expansion is that the judges Trump is appointing aren't just conservative in a jurisprudential sense. They're political partisans. There really is a difference. One is acceptable, the other is basically unworkable for Democrats.

Consider something like textualism. That's a "conservative" legal philosophy, in that it tends to cabin government power and prevent legal meanings from evolving. Still, there's no reason you couldn't write a climate law or a health law that wouldn't pass muster under textualism!

The up-and-coming Trump judges aren't textualists, though. They're Republicans. The primary criterion they use when evaluating a law is "Do Republicans like it, for whatever reason?" If Republicans do like it, it's legal. If they don't, they reason backwards to strike it down.

The problem with this is that it makes it impossible for progressives or Democrats or liberals to win in court, simply by dint of being progressives or liberals or Democrats. It's a foregone conclusion, no matter how you draft laws, pass them, or implement them.

Someone is inevitably going to say "Ah, but isn't ALL law just pretext for partisanship?" But it's not true. History is full of conservative judges who were convinced that liberals had the strongest legal claim, or vice versa, even on matters of immense importance.

But when judges are truly partisan, it becomes impossible to win those arguments. Appointing partisan judges means that the courts just become a second legislature, one that can't be voted out or changed except on a generational timespan. That's undemocratic - and unacceptable.

Faced with the possibility of the Supreme Court serving as an unelected legislature - an Upper UPPER House with lifetime appointments, almost like a peerage system - Democrats just aren't left with much choice but to alter the structure of government.

Is court expansion an ideal solution? Absolutely not. But this is part of government too: when one branch gets too big for its britches, other branches need to step in and cut it back down to size. Court expansion is simply Article I reclaiming some of its power from Article III.