WASHINGTON – Conventional wisdom now holds that Justice David Souter’s retirement may do little to change the Supreme Court’s overall ideological makeup: President Barack Obama will simply replace one liberal for another.

Predictions are dangerous, however, when it comes to the Supreme Court.

Liberal and conservative can be relative terms. They are also not necessarily the best lens through which to view Supreme Court justices who handle cases that defy standard political labels.

Personal relationships and political wiles can amplify one justice’s voice over another.

Moreover, a justice confirmed in 2009 will inevitably end up deciding issues that can’t yet be fathomed.

“There’s a tendency in this process to be very shortsighted and say, ‘The court has been fighting over abortion, affirmative action – that’s what they’re going to keep fighting over,”‘ said Jonathan Adler, a professor of constitutional law at Case Western Reserve University. “Well, maybe not.”

President Franklin D. Roosevelt, for example, picked justices such as William O. Douglas when the New Deal was hot. They ended up three decades later deciding issues relating to civil rights and the Vietnam War; Douglas was on the court until 1975.

Other predictions can go awry once a lifetime tenured justice joins the court. Souter, himself, is a prime example. Former Republican Sen. Warren Rudman of New Hampshire, Souter’s main political patron, famously assured then-President George H.W. Bush that the largely unknown Souter would be a reliably conservative vote.

Instead, Souter earned the ire of conservative activists by frequently joining liberals Ruth Bader Ginsburg, John Paul Stevens, and Stephen Breyer on decisions.

Souter’s own Supreme Court hero, Oliver Wendell Holmes Jr., became famous for angering President Theodore Roosevelt by opposing Roosevelt’s trust-busting powers.

“Justice Souter’s political legacy is that Republicans felt he betrayed the conservative cause,” noted Goodwin Liu, a former Supreme Court clerk, who now teaches at the University of California’s Berkeley Law School.

Souter’s replacement is virtually certain to confront crucial national security issues including ongoing questions over U.S. treatment of detainees. The new justice will likewise face an ongoing shift in how much power the federal government may have relative to the states.

Executive power disputes are not only certain, but also will frequently defy conventional liberal vs. conservative stereotypes. For instance, Obama and Solicitor General Elena Kagan, who has been mentioned as a potential replacement for Souter, are both sympathetic to robust executive branch powers that some liberals fear.

In other cases, the Supreme Court will have to provide followup to earlier rulings that contain lingering legal questions. For instance, the landmark 2008 D.C. v. Heller case upheld an individual constitutional right to own firearms.

Further demonstrating that important cases can defy simple left vs. right analysis, then-candidate Obama supported the court’s reasoning in Heller, while Souter opposed it.

An individual justice’s clout, moreover, can rise and fall depending on his or her political skills and ability to build alliances and sustain relationships within the court’s hothouse atmosphere.

Former California Gov. Earl Warren wasn’t famous as an attorney, but he had unparalleled political skills that helped him to command majorities in landmark cases such as Brown v. Board of Education. Obama himself cited Warren as having the kind of “empathy” he is looking for in a Supreme Court Justice.

“I will seek someone who understands that justice isn’t about some abstract legal theory or footnote in a casebook,” Obama said Friday. “It is also about how our laws affect the daily realities of people’s lives, whether they can make a living and care for their families, whether they feel safe in their homes and welcome in their own nation.”

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