With all eyes on Chief Justice William Rehnquist and his potential decision to retire from the Supreme Court, the Senate is on the verge of what could become another historic donnybrook of a Supreme Court confirmation battle.

And as with all other judicial confirmation fights, what’s past is prologue. The framework for the first Supreme Court fight of the 21st century will be solidly rooted in the battles of the past half century.

Since Roll Call began publishing 50 years ago, the Senate has been faced with two dozen nominations to the Supreme Court. They include 22 men and women, since Justices Abe Fortas and Rehnquist were nominated once for associate justice and once for chief justice.

In that span, five of those nominations, a little more than 20 percent, have been rejected by the Senate, according to a report prepared by the Senate Historical Office in 2003.

Just as many, five, cleared the chamber by an unrecorded voice vote. And four more received a unanimous roll call vote in support of confirmation, most recently Justice Anthony Kennedy, who was confirmed 97-0 in February 1988.

In looking ahead to the looming Supreme Court fight, however, the combatants on each side will surely scrutinize the toughest battles of the past, the activists on each side, and the roles played by Senate Republicans and Democrats. In addition, there will be plenty of talk about how certain lower-court nominees were treated.

Given the upcoming battle, Roll Call decided to take a look at the biggest judicial nomination battles of the past 50 years. A variety of experts on the right and left were consulted for their views, including C. Boyden Gray, White House counsel under then-President George H.W. Bush during the Clarence Thomas confirmation, and Ralph Neas, president of People for the American Way and a leader of the opposition to many of the nominees from then-Presidents Ronald Reagan, George H.W. Bush and the current President Bush.

In addition to other aides and activists, Roll Call sought the views of a few key players in the Senate, including two former chairmen of the Judiciary Committee, Sens. Orrin Hatch (R-Utah) and Joseph Biden (D-Del.).

Here is a recap of the most compelling confirmation battles for the Supreme Court and the circuit courts during the past 50 years. We present them in chronological order.

Abe Fortas for Chief Justice, 1968

Fortas was a longtime pal of then-President Lyndon Johnson, having represented Johnson before the Supreme Court in his disputed 87-vote win in the 1948 Democratic primary for an open Senate seat. Fortas won an appointment to the court in August 1965 on a unanimous voice vote. But when Johnson, a lame-duck president in 1968, tried to elevate Fortas to chief justice, Republicans revolted, joined by a bloc of Southern Democrats as well.

His closeness to Johnson was already an issue when questions arose about a $15,000 speaking fee Fortas accepted from American University’s law school, according to a recap of the nomination at an independent legal Web site (www.nationmaster.com/encyclopedia/Defeated-nominees-to-the-U.S.-Supreme-Court).

What resulted was a bitter battle whose result reverberated during the recent fight over banning filibusters of judicial nominees. After four days of debate, a cloture vote was held to cut off debate and end any potential filibuster. The vote was 45-43, with 10 Republicans and 35 Democrats voting for cloture and 24 Republicans and 19 Democrats voting against cloture. The 12 other remaining Democrats were not present. Fortas’ nomination was withdrawn — the first judicial nominee to lose out after a successful filibuster.

Clement Haynsworth for Associate Justice, 1969

Fortas resigned his associate justice seat in early 1969 amid another scandal about speaking fees. That set up a nomination for President Richard Nixon — one that soon turned into a dual rejection.

First, Nixon picked Haynsworth to succeed Fortas as associate justice. The fight focused on Haynsworth’s views on race and segregation, as well as some questions about conflicts of interest. Some present-day legal scholars likened the Haynsworth fight to the battle over confirming Charles Pickering to an appeals court seat earlier this decade.

Haynsworth lost 45-55, becoming the first nominee for associate justice of the Supreme Court to lose or have his nomination withdrawn since the Hoover administration.

Harrold Carswell for Associate Justice, 1970

The Carswell fight followed immediately after Haynsworth’s nomination failed, beginning shortly after New Years and ending in the early spring. As Haynsworth did, Carswell faced charges of supporting segregation. The result was almost exactly the same: rejected, 45-51.

What made this failed nomination enormously important in legal history was Nixon’s decision, after two straight defeats, to accommodate his Senate opponents and settle on a nominee who could win confirmation. That nominee was Harry Blackmun, who had served as best man at the wedding of then-Chief Justice Warren Burger.

Blackmun was confirmed, 94-0, on May 12, 1970. Less than three years later he wrote the landmark opinion in Roe v. Wade that still angers conservative activists to this day.

“That was a tremendous mistake,” Hatch said recently of the Blackmun nomination. “All the president had to do was put a good nominee up.”

William Rehnquist for Chief Justice, 1986

With a couple of fights over lower court nominees serving as a warmups — including the defeat of Jeff Sessions to be a U.S. District Court judge, a decade before he went on to win a Senate seat — the Rehnquist fight was the first battle of the 1980s in which the broad liberal coalition of women’s groups, civil rights groups and other activists banded together to oppose a Supreme Court nominee.

Led by Neas, who was then at the Leadership Conference on Civil Rights, and Nan Aaron of the Alliance for Justice, the activists agreed with Biden, who was Judiciary’s ranking member, to put all their muscle into stopping Rehnquist’s replacement of Burger as chief. That left little ammunition to fight against the nomination of conservative jurist Antonin Scalia, then a member of the D.C. Circuit Court of Appeals.

Confirming Rehnquist took almost three months. Democrats forced a cloture vote on Rehnquist, which he won, thus killing off any filibuster attempt. He was confirmed, 65-33, on Sept. 17.

Later that same day, Scalia was confirmed 98-0 to be associate justice, and he went on to become a forceful voice for conservative principles on the court. Neas recently lamented this result to reporters at a PFAW briefing. He promised that if Scalia is nominated for chief this summer, the left would muster the energy to fight a two-front war against Scalia and whoever the new nominee was.

Robert Bork for Associate Justice, 1987

Widely regarded as the biggest judicial battle of the century, and maybe ever, Bork’s nomination was a perfect storm for liberals who opposed to it.

When he worked in Nixon’s Justice Department, he carried out the “Saturday Night Massacre” by firing Special Counsel Archibald Cox in 1973. Bork was also a prolific legal writer as solicitor general, in the private sector and then on the D.C. Circuit. His writings were colorful and controversial, and solidly conservative.

“No White House had ever faced anything like this before,” recalled Gray, who was at the time counsel to then-Vice President George H.W. Bush. While the Haynsworth and Carswell fights were tough, they largely played out inside the Beltway. Suddenly, with C-SPAN and CNN now bringing the Senate to televisions everywhere, liberal activists turned the Bork nomination into a national campaign. At one point his home video rental lists were leaked to the media.

When he lost the support of Judiciary Republicans such as Sen. Arlen Specter (Pa.), Bork couldn’t even muster a positive recommendation from the committee. Three and a half months after his nomination, he was defeated, 42-58, the most lopsided Supreme Court defeat in a roll call vote in the 20th century.

Clarence Thomas for Associate Justice, 1991

The Thomas hearings became a media moment of their own — a combustible mix of legal and political issues blended with race and workplace sexual politics.

The defining moment came when Anita Hill, a former aide to Thomas in the early years of the Reagan administration, accused him of sexually harassing her during nationally televised Judiciary Committee proceedings.

The hearings became fodder for “Saturday Night Live” skits, but also more importantly made sexual harassment a household word. Thomas, who is black, fought back, denying the accusations and comparing the process to a “high-tech lynching.”

He ultimately won a hard-fought confirmation — 52-48 in a chamber then controlled by Democrats — but the battle had a ripple effect on the 1992 election cycle.

In what came to be called the “Year of the Woman,” a record number of women were elected to the Senate, including Barbara Boxer (D-Calif.), who had led House Democratic women’s opposition to Thomas, and Carol Moseley Braun, who ousted incumbent Alan Dixon (D-Ill.) in a primarily largely based on his vote supporting Thomas.

While most conservatives consider the Bork defeat their low-water mark, Hatch said recently that the Thomas fight was the “all-time low” in which he accused the opposition of “hitting below the belt.”

Richard Paez to the 9th U.S. Circuit Court of Appeals, 1996-2000

While the Supreme Court wars settled down during Bill Clinton’s presidency — Ruth Bader Ginsberg and Stephen Breyer were confirmed for associate justiceships without much controversy — Senate Republicans regularly put up aggressive fights against Clinton’s circuit court nominees. Democrats accused Republicans of using delaying tactics to derail about 60 nominations.

Paez became the poster child for these fights because it took four years for him to get confirmed. Republicans widely viewed Paez to be too liberal, and were wary of confirming him to a 9th U.S. Circuit Court of Appeals they viewed as already being too liberal.

Ultimately, despite pleading from then-Majority Leader Trent Lott (R-Miss.), Paez’s staunch opponents forced a cloture vote and thus allowed Democrats to accuse them of attempting to filibuster the nomination.

Paez won the cloture vote 85-14, with Sen. Bill Frist (R-Tenn.), then a backbencher, joining Smith and dozen other conservatives voting to sustain the filibuster.

Priscilla Owen to the 5th U.S. Circuit Court of Appeals, 2001-2005

Senate Democrats in the first term of President Bush filibustered 10 circuit court nominees and were set to block up to a half dozen more, but Owen became the signature nominee of the conflict. Owen’s glide path hit a major road block when Democrats seized control of the chamber after Sen. Jim Jeffords (I-Vt.) switched parties.

Emboldened by their new majority, Judiciary Democrats voted down Owen’s nomination in committee, as they did to several other nominations, including Miguel Estrada and Charles Pickering Sr.

Back in control after the 2002 midterms, Republicans pushed Owen out of committee and onto the Senate floor, where, like Estrada and Pickering, she was filibustered by Democrats. Those nominations made history as the first rejected judicial nominees to be defeated in committee and then filibustered in a later Congress.

Estrada and Pickering bowed out, but Owen agreed to be resubmitted in the winter of 2005. As Frist, now Majority Leader, crafted a historic showdown on eliminating judicial filibusters, he made Owen the test case in mid-May.

Throughout the debate, each side reached back into history to defend its actions, with Democrats citing the Fortas filibuster for their circuit court blockade and Republicans citing the up-or-down votes on controversial nominees such as Thomas as evidence for why filibusters should not be permitted.

Eventually, a “Gang of 14” Senators — seven Republicans, seven Democrats — forged a compromise that allowed for some previously blocked nominees to get confirmed in exchange for retaining the right to filibuster in “extraordinary” circumstances.

On May 26, Owen — having won a cloture vote with 81 votes two days before — was confirmed, 55-43.