The latest confrontation in the judicial confirmation wars occurred Tuesday when Senate Republicans blocked the nomination of Nina Pillard to the U.S. Court of Appeals for the D.C. Circuit. Pillard was the second such nominee to that court denied in the past two weeks, producing yet another round of saber-rattling over the Senate’s filibuster rules.

On a 56 to 41 roll call, Pillard fell four short of the threshold to clear a GOP filibuster; just two Republicans supported ending debate to move to a final vote on her nomination.

For all their intensity, there is nothing particularly new about these nominations fights. Both sides have been at war for years over the federal appellate courts in general, and the D.C. Circuit in particular.

The battle has been going on so long that it is difficult to discern who fired the first shot and when.

Among the early casualties was Chief Justice John G. Roberts Jr. — but not for his 2005 Supreme Court confirmation or his brief stint on the D.C. Circuit a decade ago. In the early 1990s, President George H.W. Bush nominated Roberts to the elite D.C. bench, and Democrats responded by leaving his nomination in limbo until Bush lost his reelection bid. Justice Elena Kagan received the same treatment when President Bill Clinton nominated her to the D.C. Circuit in 1999, but Senate Republicans allowed her to languish until the GOP took back the White House in 2001.

Roberts and Kagan are proof that there is life after a blocked nomination to the D.C. Circuit. Both ultimately won confirmation to Supreme Court — in 2005 and 2010, respectively. They were defeated initially by hostile Senate majorities — Democrats in the early 1990s holding up Roberts and Republicans in the late 1990s with Kagan.

Their nominations simply never received a vote then.

Tuesday’s roll call was different, a power play by the minority. Republicans signaled weeks ago that they would filibuster Pillard or anyone nominated to the D.C. Circuit on the belief that the court does not need more judges. Judicial filibusters are a rare way to block a nominee, but one in which both sides have blood on their hands.

Pillard would become the fourth of President Obama’s circuit court nominees to be filibustered, following 10 nominees to the circuit courts by President George W. Bush who were filibustered by Senate Democrats. Several of those Bush judges ultimately were confirmed after a mid-2005 deal brokered by centrist Republicans and Democrats, who defused an effort by GOP leaders to unilaterally change Senate rules to allow for a simple majority to confirm judges.

Eight years later, it is the Democratic leaders threatening to change the rules to install Obama’s judicial nominees by a 51-vote majority. After the Pillard filibuster, Sen. Richard J. Durbin (Ill.) called it a “tipping point” toward a rules change. Sen. Patrick J. Leahy (Ill.), the Judiciary Committee chairman who led Democratic filibusters in the George W. Bush era, pounded a lectern and said of GOP senators who helped unwind recent rules showdowns: “Their credibility is shred.”

How did it get this way?

“Most folks don’t know or remember, but it does seem that both parties share responsibility, and each has ratcheted up the stakes,” said Carl Tobias, the Williams professor at the University of Richmond School of Law, an expert on the confirmation process.

The Pillard vote comes 45 years after the first filibuster of a judicial nominee, the failed effort by President Lyndon B. Johnson to elevate Justice Abe Fortas, his friend, to chief justice of the United States. That, however, was a rare bipartisan filibuster, in which Southern Democrats, including Sen. Richard Russell (Ga.), joined Northern Republicans, such as Senate Minority Leader Everett Dirksen (Ill.), in rejecting Fortas.

Tobias noted, however, that the judicial confirmation process has always been ugly. In the 19th century, almost a third of all Supreme Court nominees were not confirmed by the Senate. Fortas failed to clear the super-majority threshold for a filibuster, but in reality, he would have been rejected by a majority of senators, as happened with President Richard M. Nixon’s first two nominees to the Supreme Court. In the modern, televised era of the Senate, the first flash point came in the nomination of Robert H. Bork to the Supreme Court in 1987. Before a Judiciary Committee led by Sens. Joseph R. Biden (D-Del.) and Edward M. Kennedy (D-Mass.), Democrats thundered against Bork’s conservative writings.

Bork refused to withdraw, and the Senate rejected him on a 42 to 58 vote.

The historical importance of the Bork nomination fight cannot be overstated. President Ronald Reagan filled that vacancy with Anthony M. Kennedy, who served on the California-based U.S. Circuit Court of Appeals for the 9th Circuit. He was easily confirmed and over the past two decades has become one of the two most important swing votes in most major cases — the opposite of how Bork’s tenure probably would have gone.

Not long after Bork, both sides realized that the battle for the judiciary’s soul had as much to do with the appellate courts, because they served as the proving ground for a Supreme Court nomination. In 1982, Bork’s nomination to the D.C. Circuit came and went with little fanfare, winning an easy confirmation, unlike his Supreme Court bid five years later.

Bork retired from the D.C. bench in 1988, and the nominee to replace him was a little-known George H.W. Bush administration official, Clarence Thomas. He sailed through his 1990 confirmation process to the D.C. appellate court. By the fall of 1991, in another epic showdown, Thomas narrowly won his Supreme Court confirmation.

Eight of the nine current justices came to the bench from an appellate court seat; Kagan is the exception, and that’s only because Republicans blocked her 1999 nomination. Four of the justices served on the D.C. Circuit.

In 2001, the George W. Bush White House nominated a member of House GOP leadership, Rep. Christopher Cox (Calif.), to the 9th Circuit, but Sen. Barbara Boxer (D-Calif.) used an unknown senatorial courtesy called “blue slipping” to torpedo him. Under Judiciary Committee procedures, senators are allowed to approve or veto nominees from their home states. Approval is delivered in the form of a blue slip returned to the committee by the senator.

Boxer considered Cox too conservative, particularly on abortion rights, and never returned her blue slip. Less than a month after his nomination, Cox withdrew, never having received a full background check, let alone a hearing or vote.

Twelve years later, according to the liberal Alliance for Justice, Republican senators, particularly those from Texas and Pennsylvania, have taken the blue-slip privilege to new levels. Those two states account for 50 percent of the vacancies on circuit courts where there is no nominee.

Tobias said neither side has the purest of motives, but Republicans’ objections to appointing anyone to the D.C. Circuit is another step deeper into the breach.

“The GOP is plumbing new depths by filibustering anyone nominated,” Tobias said, noting that Democrats did help appoint four Bush-era nominees to that court. “At least Dems’ opposition was based on specific nominees’ records, not the number of judgeships.”