The Supreme Court today ruled that judges who are elected must recuse themselves in "extreme" cases -- those in which the contributions to the judge's campaign are so large that they create the perception of bias.

From the Washington Post :

"Not every campaign contribution by a litigant of attorney creates a probability of bias that requires a judge's recusal, but this is an exceptional case," wrote Justice Anthony M. Kennedy.

The case -- the plot of a John Grisham novel -- has drawn a spotlight on the skyrocketing costs of judicial elections, especially state Supreme Court races. Justice at Stake, a judicial reform group, notes that state Supreme Court candidates -- 39 states elect judges -- raised almost $168 million from 2000 to 2007, nearly double the amount raised during the 1990s.

One the one hand, this strikes me as eminently reasonable. Judicial elections are thorny things. (I wrote about this topic in Governing a couple years ago.) As spending levels in these campaigns have skyrocketed, some advocates worry that the judiciary is becoming more and more partisan. They worry that judges who get into office bankrolled by deep-pocketed contributors can't possibly approach cases with an unbiased mind. So forcing them to recuse themselves seems like a decent way to address those concerns.

On the other hand, though, this ruling does seem to open the door to new headaches. First off, how are judges supposed to know what qualifies as an "extreme" case? I mean, the case before the Court seemed pretty cut-and-dried: A justice in West Virginia, Brent Benjamin (now the chief justice of that state's court) twice ruled to throw out a verdict against a coal company whose CEO had spent $3 million in 2004 attacking Benjamin's opponent.

So, yeah, I think we could all agree that that at least gives the perception of impropriety. But what about lesser offenses? Where do we draw the line?