In the death penalty case argued before th ecourt on Wednesday, Justice Kennedy emerges as an important figure.

With questions and comments from the justices revealing an even split along liberal-conservative lines, the outcome could depend on Justice Anthony M. Kennedy, the centrist who is the court's swing voter now that Sandra Day O'Connor has retired.

Kennedy was in no mood for joking as he weighed Florida death row inmate Clarence E. Hill's contention that the three-drug injection used by Florida, 36 other states and the federal system risks harsh but undetectable pain.

When his colleagues engaged in some light banter, as they often do during oral arguments, Kennedy interrupted: "This is a death case. It's not that amusing."

This is a role some think Kennedy likes to play: rather than shrink from judicial power, he enjoys it. Here is a lengthy excerpt from an opinion piece earlier this month in the New York Times, Anthony Kennedy Is Ready for His Close-Up, that should resonate with us as we are reading Keck:

When the right cases reach the court, Justice Kennedy could provide the deciding vote to declare campaign finance restrictions of all kinds unconstitutional, to end affirmative action and to uphold greater limitations on abortion rights. He may well relish the chance to finally get his way on these issues. But there are also reasons to believe that, at least in some cases, he may not.

For one thing, there are signs that his views are evolving. Last year, he wrote the decision ending the juvenile death penalty, reversing his 1989 position. And he has become an increasingly strong advocate for taking international law into account, to the distress of many conservatives.

He is also someone who cares what other people think. The Supreme Court scuttlebutt has always been that he is open to persuasion by colleagues, and even law clerks. It is sometimes said condescendingly, but there is something refreshing about a justice who genuinely seems to have an open mind. When he switched sides on the juvenile death penalty, he wrote a thoughtful opinion noting both that the American people had turned against it and that "the overwhelming weight of international opinion" opposed it.

Perhaps most important, it is not yet clear how Justice Kennedy will be changed by his vastly expanded influence. Justice O'Connor was very aware of her position as the swing justice, and it made her deeply aware of the impact her votes had on real people's lives. Justice Kennedy may inherit that mantle of concern. It is one thing to argue in dissent that campaign finance laws violate the First Amendment. It is quite another to cast the vote that prevents a nation weary of lobbying scandals from trying to clean up its elections.