Sometime in late June, John Paul Stevens will retire from the Supreme Court as the second-longest-tenured justice in that body's history. The only justice to have served longer is the man he replaced, William O. Douglas.

As Barack Obama seeks to fill his second Supreme Court vacancy in just 14 months in office, Stevens' appointment serves as a cautionary tale for presidents considering Supreme Court nominees on an ideological basis.

In selecting Stevens, President Gerald Ford believed he was -replacing the notoriously combative liberal Douglas with a reliable conservative. But as with Richard Nixon's appointment of Harry Blackmun and George H.W. Bush's appointment of David Souter, Stevens never lived up to his conservative -credentials. Instead, he leaves the bench as the elder statesman and best tactician of the court's liberal wing.

Few presidential powers have more lasting impact than the power to -nominate Supreme Court justices. Once confirmed, they can serve for a generation and affect the course of history for centuries. Supreme Court nominations are a big deal. And in these contentious times, a partisan showdown, regardless of whom the president nominates, is to be expected.

The old fight was over reproductive rights as addressed in Roe v. Wade. To a large extent, it still is. But the way that case was decided, in a ruling that set the terms for when it was legally -permissible for a woman to have an abortion, is regarded as "judicial activism" - a power, its critics argue, that the constitution never intended. In the weeks ahead, you will hear a lot about judicial activism.

Most often, you'll hear it from the right but what constitutes judicial activism is largely a matter of perspective.

If you tuned in to NPR or CSPAN for their confirmation hearings, you could have heard George W. Bush's nominees, John Roberts and Samuel Alito, profess their fidelity to the concept of stare decisis (which is a fancy way of saying "adhering to precedent"). But that -wasn't enough to stop them from -overturning 20 years of precedent in their ruling in the case of Citizens United v. FEC.

In a 5-4 decision, the court asserted that corporations have the same -political advocacy rights as individuals, effectively concentrating more power in the hands of those who already -wielded the most power. In his dissenting opinion, retiring Justice Stevens wrote, "The court's ruling threatens to undermine the integrity of elected -institutions across the nation. The path it has taken to reach its outcome will, I fear, do damage to this institution."

For average citizens, the decision -rendered in Citizens United v. FEC is judicial activism of the worst kind. It is a ruling that would have been unthinkable in the hundred years before Roberts and Alito replaced William Rehnquist and Sandra Day O'Connor respectively.

Despite its potential for abuse, -judicial activism is essential to our democracy. How much longer and bloodier would the struggle for civil rights have been were it not for the decisions of men (most of these decisions were made before there were women on the court) who faced no political repercussions for doing what their conscience and justice demanded?

Is it at all certain that three of our sitting justices and two past justices would even have had the opportunity to serve were it not the foresight of activist judges and justices?

Martin Luther King Jr. assured us that "The arc of history is long ... but it bends toward justice." It has been suggested that President Obama should choose the candidate that will least provoke the loyal opposition. It would be an uncharacteristic mistake to choose expedience over justice.

Nations evolve. There will inevitably be cases in which the status quo can no longer pass for justice. We will always require the service of individuals with the character and fortitude to bend the arc of history.

Kevin Smith lives in Aberdeen. Contact him at kevinasmith@gmx.com.