A new appointment to the court could signal the end of that swing vote role for Justice Kennedy in most controversial cases. In the court term that ended last June, Kennedy provided the fifth vote in 14 of the 16 cases decided by a 5-4 margin. In the term ending in 2010, he was the controlling vote in 12 out of 17 cases decided 5-4. In the 2009 term, he was the fifth vote in 20 of 25 cases with a 5-4 margin.

Often, Kennedy is on the so-called conservative side of cases with the liberal bloc of Justices Breyer, Ginsberg, Sotomayor, and Kagan facing off against the conservative wing of Justices Roberts, Scalia, Thomas, and Alito. Examples include: Bush v. Gore, Citizens United (voiding Congressional limits corporate and union election expenditures on First Amendment grounds), and a case voiding District of Columbia gun control provisions under the Second Amendment. He has also sided with the liberals in, for example, cases striking down sodomy laws under the constitution, declaring the death penalty unconstitutional for juvenile offenders (citing principles from foreign jurisdictions) and ordering the release of thousands of prisoners in overcrowded California jails under the 8th amendment's prohibition against cruel and unusual punishment.

Advocates practicing before the Supreme Court must direct an important part of their argument to Justice Kennedy in order to satisfy the first principle of successful lawyers before the high court: being able to count to five. Certainly, those arguing in favor of health care reform have to focus first on securing Justice Kennedy's vote (they assume Justices Ginsburg, Breyer, Sotomayor, and Kagan will vote to uphold).

Here is how Justice Kennedy's importance could be severely reduced after the 2012 election.

If a Republican is elected president and if a member of the court's liberal bloc leaves the court, then the new chief executive would nominate a more reliable conservative justice, in the mold of Justice Roberts or Justice Alito (George W. Bush's appointments). Were such a person confirmed, there would be a solid five-vote conservative majority without Justice Kennedy, who would lose his swing vote position and his ability to influence the holding of the conservative majority in 5-4 cases.

If President Obama is re-elected and if a member of the court's conservative bloc leaves the court, then Obama would nominate a reliable (if moderate) liberal justice, like his earlier appointments of Justice Sotomayor and Justice Kagan. Were such a person confirmed, there would be a solid five vote liberal majority without Justice Kennedy, who would, again, lose his influence in shaping or defining the liberal rule of the case in major constitutional matters.

Just to preserve the status quo, it is also important for conservatives to have a conservative president nominate a conservative justice for a vacancy in a conservative seat. The opposite is true for liberals.

It is, of course, impossible to predict whether the president elected in the fall will have a Supreme Court vacancy. The ages of the Justices vary widely -- from 51-79 -- but health problems or other issues can occur at any time.

One thing is for sure: If there is a vacancy and one of the two scenarios outlined above occurs, there will be a titanic confirmation fight. The stakes are that high.

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