NO one,'' a legal aphorism tells us, ''shall judge his (or her) own case.'' Fairness and common sense agree. Only in Utopia could you expect a judge to rule against self-interest, and that territory lies beyond the jurisdiction of any sitting judge.
This moral precept is easy to apply, but only in plain cases - the sort that almost never occur. A judge would not hear a case in which he were plaintiff or defendant. Nor would he hesitate to recuse - disqualify - himself from any matter directly involving a close relative.
It is the shaded situation that gives trouble. Take that supposedly ''plain'' case of the family-member litigant. What does ''directly'' mean? How about ''involving''? How near is ''close''? For that matter, when is a judge himself affected by the outcome of a case?
Not long ago, I had to decide the legality of a Massachusetts regulation concerning the grain pesticide EDB. Everyone conceded that EDB is toxic. The regulation's opponents argued only that the tolerance level that the state had set was impermissibly low.
Whatever the legal issues of the controversy, the dispute unquestionably concerned a serious question of public health, affecting everyone who eats grain products. I enjoy a daily bowl of cereal and an occasional bit of bread. Yet it never occurred to me that I should not hear the case. And although the decision provoked considerable interest (and a reversal by the Massachusetts Supreme Judicial Court), nobody suggested that my errors included a failure to recuse.
But suppose the judge orders a town to spend public funds to clear up an improperly maintained dump. If the judge owns land in the town, will the decision affect his financial interest in minimizing the tax rate and thus require him to shunt the case elsewhere?
As you can see, if a judge does not begin to shade, he will soon find himself disqualified in numerous matters. And if he shades too carelessly, he may slide into conflict of interest.
Bear in mind that a court must not only do justice; it must also appear to be doing justice. To some extent, in weighing recusal, a judge has to ask, ''How will this look?'' One of my colleagues proposes the ''front-page test'': Would the judge be comfortable if the decision not to recuse and the facts underlying it appeared tomorrow under thick headlines? If the answer is anything short of a hearty ''Yes,'' he leaves the case.
Unfortunately, too easy a resort to disqualification causes other problems. A judge therefore must also bear in mind Aldrich's principle (named for the wise federal judge Bailey Aldrich): The judge's obligation to sit, when grounds for recusal are absent, is at least as strong as the obligation to recuse when such grounds are present.
A judge who abandons litigation, even validly, is automatically putting the matter onto some other judge's back. Further, if the request for disqualification comes from counsel, a judge must ponder whether the attorney's real aim is merely to knock this particular judge out of this particular litigation.
That ploy is called judge-shopping. Candor compels me to note its judicial analogue: case ducking. If for whatever reason a judge would prefer not to deal with a pending matter, a colorable issue of self-interest is the means of exit least likely to provoke adverse comment.
Sometimes merely airing a potential recusal problem dissipates it. Thus in appropriate cases I state on the record that when I was in law school two armed, self-liberated convicts took me and the car I was garaging to the other end of the state where they released me unharmed but kept the car and the contents of my wallet. No one has yet moved for recusal.
A judge I know was about to begin a complicated and lengthy nonjury case - a judicial pet hate. The night before trial, the judge's mother-in-law casually mentioned owning a minuscule amount of one party's publicly held stock. Had the judge owned even one share a statute would have effected automatic disqualification; the law was silent, however, about in-laws.
At the next day's proceedings, the judge announced: ''I have a mother-in-law problem,'' then stated the facts and said, ''call your first witness.'' This treatment combined the front-page test and Aldrich's principle with the prescient philosophy of Yale's legendary football coach, Herman Hickman: ''If they're looking to run you out of town on a rail, be sure to lead the parade.''