Judicial-Judicial Small Change Tolerance Slippery Slopes and the Extension of Precedent

[This month, I'm serializing my 2003 Harvard Law Review article, The Mechanisms of the Slippery Slope.]

Just as precedents can be extended beyond their original terms through equality slippery slopes and attitude-altering slippery slopes, they can also be extended through small change tolerance slippery slopes.

Legal rules are often unavoidably vague at the margins. Even when a rule usually yields a clear result, there will often be some uncertainty on the border between the covered and the uncovered. If, for instance, a new free speech exception allows the punishment of "racial, sexual, and religious epithets," some speech (for example, "nigger" or "kike") would pretty clearly be covered. Other speech (for example, "blacks are inferior" or "Jews are conspiring to rule the world") would clearly not be covered. For other speech (for example, "Jesus freak" or "Bible-thumper" or "son-of-a-bitch"), the result might be uncertain. {Some readers might conclude that some words in this last example are clearly epithets and other words are clearly not, but I suspect others would disagree. My point here is a descriptive one—that the result would indeed be uncertain—and not that the result should be uncertain.}

In such situations, the judge deciding each case has considerable flexibility. The test's terms and the existing precedents leave a zone of possible decisions that will seem reasonable to most observers. If the judge draws the line at any place in that zone, most observers won't much complain. This is a small change deference heuristic: if the distance between this case and the precedents is small enough, defer to the judge.

There can be various causes for this deference. Judges on a multi-member panel may defer to an authoring judge's draft opinion because they know that they can't debate every detail of the many cases that need to be decided; this isn't rational ignorance as such, but more broadly rational management of the court's time. Judges may also be reluctant to alienate sometimes prickly colleagues, with whom they must regularly work, by fighting seemingly minor battles. Thus, while each judge may in theory review the authoring judge's draft de novo, in practice there's some deference. And this effect will be even greater when judges are deciding whether to rehear a case en banc, where deference to the panel opinion is part of the rule.

Future judges who aren't bound by the precedent (either because they're on another court or because they're considering a case that is a step beyond the precedent) may also be more easily influenced by a past decision that makes only a small change. If a judge sees that the precedents imposed liability in four fairly similar situations A, B, C, and D, the judge may quickly conclude that the dominant rule is liability in all situations falling between A and D. If the judge sees that the precedents imposed liability in three similar situations A, B, C, and in a very different situation Z, the judge may be more likely to look closely and skeptically at the big change Z. This deference to closely clumped decisions is probably a rational ignorance effect—because judges, law clerks, and staff attorneys lack time to closely examine the merits of every potentially persuasive precedent, they spend more of their skepticism budget on outlier cases than on the ones that seem more consistent.

Decisions that make small changes may also be less criticized by academics or journalists. An article saying that some decision is a small change and a slight mistake is less interesting to write, and less likely to be read and admired, than one saying that another decision is a big change and a big mistake.

This effect may be strengthened to the extent that laypeople, lawyers, and other judges view judges as professionals exercising technical judgment within a system of rules. Deferring in some measure to people who are exercising professional judgment is usually seen as good sense and good manners. If that judgment diverges substantially from those reached by the professional's peers, observers may review the judgment more skeptically. But if the judgment diverges only slightly from past decisions, observers might tend to defer, even if they wouldn't fully agree were they reviewing the issue de novo.

And this effect is not limited to changes that are part of a judge's deliberate campaign to alter some legal test. Some small changes can happen simply because judges are faithfully trying to apply a vague rule, and conclude that the rule should extend a bit beyond its previous applications (especially if extending the rule is viscerally appealing, perhaps because one side in the typical case seems so sympathetic). Moreover, judges' ingrained habit of defending their decisions as being fully within the precedents may lead them to downplay—even to themselves—the broadening of the rule, and to describe the rule as having been this broad all along.

Thus, because of small change tolerance, a legal rule may evolve from A to B to C to D via a judicial-judicial slippery slope, even if legal decisionmakers would not have gone from A to D directly. And just as with legislative-legislative slippery slopes, those who strongly oppose D might therefore want to try to stop the process up front by arguing against A in the first place.