In a review of a book of Justice Homes' dissents, from the May 1930 issue of American Mercury, Mencken wrote "Laws are no longer made by a rational process of public discussion; they are made by a process of blackmail and intimidation, and they are executed in the same manner. The typical lawmaker of today is a man wholly devoid of principle---a mere counter in a grotesque and knavish game. If the right pressure could be applied to him he would be cheerfully in favor of polygamy, astrology or cannibalism. It is the aim of the Bill of Rights, if it has any remaining aim at all, to curb such prehensile gentry."
Mencken's reason for discussing this is that Mencken said Holmes was too deferential to legislators. Mencken said Holmes allowed legislators too much "headroom."
We mean by "activist judges" is that judges are not adequately deferential to legislative majorities. At least, maybe that's what "activist" means. If that's true, Holmes would not be classed as "activist."
Mencken's point is that legislators are too easily swayed by pressure of one sort or another. Therefore, deference to judges is not appropriate, Mencken thought, because the legislators are not using their own independent good judgment. Said differently, if legislators did a better job of legislating, then there would be more reason for judges to defer to them. As it is, Mencken thought, judges should try to make up for the deficiencies of the legislators, not defer to them.
In New York, we have just had a flap about letting non-US citizens drive. The hysteria about "illegal" aliens and the federal government's mindless frenzy to mistake Mexicans for "Islamofascist" terrorists doomed Governor Spitzer's plan to allow drivers to be properly licensed. If our government had a more rational tinge, we might say that it was a good thing to cause automobile drivers to be properly licensed. As it is, the hysteria has pushed the governor to keep unlicensed drivers on the road. If immigration policy were more rational, then we would not be confusing safety on the highways with enforcement of irrational immigration status rules. As it is, we surrender highway safety to hostility to individuals who don't look like people who have been here a couple of generations.
Who knows what kind of "blackmail and intimidation" Secretary Chertoff brought to bear on Governor Spitzer to get the Spitzer administration to sign an agreement to enlist New York State in the national program to issue an identity card for every American. But it did not take long for Spitzer to cave in to this radical change in traditional American values.
Anyway, that must be the kind of thing that Mencken thought should not trigger judicial deference to lawmakers. Mencken's insights into his time relate to our times. You don't have to look far to find "prehensile gentry."