In 1987, Robert Bork became the target of an organized, special interest smear campaign aimed at ruining his chances for being confirmed by the Senate as a Supreme Court justice.   Since then, a tit-for-tat approach has made Supreme Court appointments a political football.

These politicized Supreme Court nomination battles have eroded public support of the high Court and a study of public reactions during the Samuel Alito nomination process shows it is only going to get worse.

In a new book, researchers reveal how television advertisements that opposed Alito's nomination in 2005 had a disturbing side effect: Many people who viewed those highly political ads become less supportive of the Supreme Court as an institution.

The reason seems to be that, in the minds of many viewers, the ads reduced Supreme Court justices to just "politicians in robes," said Gregory Caldeira, co-author of the book and professor of political science at Ohio State University.  "Americans have long believed that Supreme Court justices are above politics.   Anything that drags the Court into ordinary politics, such as these ads, damages the esteem of the institution."

The results of this study have renewed significance now, with the recent nomination of Sonia Sotomayor to the high Court,  Caldeira said.  

The Sotomayor nomination may not generate as many ads from partisan interest groups as the Alito nomination did because she is Hispanic – a critical constituency for both Republicans and Democrats.  But for proponents of abortion or racial quotas, for example, the makeup of the Supreme Court is an especially big issue, and that may lead some conservative groups to believe it is worth it to attack Sotomayor as too liberal.

"If interest groups air attack ads against Sotomayor, that could undermine some of the public support for the Supreme Court, just as they did against Alito," he said.

In the summer of 2005, the researchers surveyed a representative group of 1,001 Americans concerning their knowledge and beliefs about the U.S. Supreme Court. When Chief Justice William Rehnquist died in September 2005, the researchers knew they had an opportunity to study how the nomination of a new justice would affect public opinion of the Court.

In January 2006, the researchers re-interviewed more than 300 of the original survey participants to see if their views of the Supreme Court changed after the nomination of Samuel Alito, who became a justice on January 31, 2006.

Many participants were interviewed a third time in May and June 2006.

In the first survey, about 69 percent of participants showed general support for the Supreme Court, researchers found. But substantial proportions of Americans changed their views of the Supreme Court after the Alito nomination.

About 36 percent of those surveyed showed less support for the Court after the nomination, 24 percent stayed the same, and 39 percent showed more support.

Caldeira said that in an analysis of these results, one result stood out: People who saw ads by interest groups either promoting or denouncing Alito's nomination were most likely to become less supportive of the Court as a whole.

"Those who saw a greater number of advertisements became substantially less supportive of the Court," he said.

The results had nothing to do with people just paying closer attention to the nomination process and simply seeing more ads, according to Caldeira. In fact, the more attention people paid to the confirmation battle, the more supportive they were of the Court -- as long as they didn't view many of the ads.

The ads did their damage by defying the image people had of the Court as being non-partisan and, indeed, "above" politics, Caldeira said.

That interpretation was clear in the results: the more that participants supported the Supreme Court before the Alito nomination, the more likely they were to judge the advertisements to be unfair, negative and partisan.

"The ads ran counter to how people perceived the Supreme Court justices," Caldeira said.

One ad against Alito's nomination, for example, claimed Alito "even voted to approve the strip-search of a ten-year-old girl … The Right Wing has already taken over the West Wing. Don't let them take over your Supreme Court."

A pro-Alito ad countered that "Everyday, desperate liberals make up a steady drip of attacks against Judge Samuel Alito."

Caldeira said, "These kind of attack ads are similar to what one would see in a congressional race. They take information out of context and frame the person as an extremist. The impression people get from watching these ads is that the Supreme Court is nothing but a set of politicians in robes."

And it wasn't just supporters of Alito's nomination who disliked the ads – opponents of his confirmation who were strong supporters of the Supreme Court were even more likely than Alito supporters to say the ads were unfair.

Partisanship and ideology were not the driving forces in determining how the nomination process affected support for the Court.

The study showed that Democrats and Republicans were indistinguishable in their levels of support for the Court, even after the nomination battle.

Caldeira said that it is highly unlikely that interest group ads about justice nominees, by themselves, could do significant, permanent damage to the Court's legitimacy.   Nonetheless, the legitimacy of the Court is a very important resource that should be protected.

"Americans accept the decisions of the Supreme Court because they see it as a legitimate judicial institution," he said. "If the Court loses that legitimacy, all Americans lose."

The study is described in the book "Citizens, Courts and Confirmations" (Princeton University Press), which Caldeira wrote with James Gibson, a professor of government at Washington University in St. Louis.