Anyone looking for lofty constitutional principles underlying the battle between Senate Republicans and Democrats over President Bush's judicial picks can find them under such headings as "checks and balances," "separation of powers" and "advise and consent."

But the sheer level of chest-pounding and acrimony is best explained by a more practical maxim: Payback's a one-syllable word that rhymes with witch.

It's an established fact that Republicans blocked more of President Clinton's court appointments than Democrats have done with Bush's -- 80.4 percent of Clinton's district court nominees were confirmed compared with 94.9 percent of Bush's so far, as were 61.3 percent of Clinton's circuit court nominees compared with 67.3 percent of Bush's.

So conservatives are not fooling anyone with their professions of indignation that Democrats would have the gall to decline to act as rubber stamps for this particular group of nominees whom they see as beyond the pale.

Clearly, the Dems want to pay Republicans back for the Clinton era by using the same filibuster technique that both parties have used in the past. Just as clearly the GOP wants to immunize itself from such payback by changing the rules.

This, of course, would allow Republicans to fill the vacancies they themselves created by digging in their heels during the Clinton era, and in so doing pack the courts with judges so far outside the mainstream that they cannot garner a filibuster-proof majority.

So when Senate Republican Leader Bill Frist said in a recent floor speech, "It's time for judicial obstruction to end. Senators have a duty to vote up or down on judicial nominations," the unspoken sub-text was "now that we're in the majority, that is."

Why should the Dems lie down for such a naked power grab? Here's what a distinguished senator once had to say about his own opposition to a president's nominee:

"The confirmation process is not a numbers game, and I will not compromise the Senate's advise and consent function simply because the White House has sent us nominees that are either not qualified or controversial. There are a range of factors which make a nominee controversial or difficult to confirm, such as lack of experience or questionable information contained in materials not in the public domain or in their past records that may be at variance with the proper role of judges in society."

The speaker was Republican Orrin Hatch on Oct. 21, 1998.

On Monday, Democrats were circulating a list of the Republican senators who had ever filibustered or blocked a nominee. The complete list is available online at www.rawstory.com under the headline "Doc: GOP senators nixed nominees."

It's much too long to reproduce here, so let's just go with a refresher course on Pennsylvania's own Rick Santorum, who blocked three Clinton nominees -- John H. Bingler Jr., Lynette Norton and Robert Freedberg -- from receiving the very same up-or-down vote that Frist now demands.

Santorum, who only made matters worse last week by calling these nominees "unqualified" (see Sunday's rebuttal letter to the Pittsburgh Post-Gazette from Donald E. Ziegler, former chief judge of the U.S. District Court), also blocked U.S. District Judge Robert J. Cindrich from the 3rd U.S. Circuit Court of Appeals.

In addition, he voted to filibuster two Clinton executive nominees, David Satcher and Henry Foster (twice); voted to block another judicial nominee, Richard Paez; and then, after the GOP filibuster was broken, voted to indefinitely postpone a vote on Paez.

Why Santorum thinks this record gives him standing to demand confirmation of all of Bush's nominations is a mystery.

Or maybe not. Politics, after all, is just one subset of human behavior, and we humans have always had among us those who live by the motto "I've got mine and now I'm going to keep you from getting yours" -- except in this case, it would be "I blocked yours and now I'm going to keep you from blocking mine."

These are the folks who move up in life while trying to prevent others from following the same path -- the ones who came here from other countries and now want to shut down immigration, who overcame bigotry but still discriminate against others, who benefitted from social programs and now want to drastically curtail them.

It's an ignoble trait that people of all political stripes have been known to exhibit. They forget that sooner or later, what goes around comes around. And when it does, payback's a witch.