One of the most eye-opening studies I’ve seen in recent years comes from Professors Kevin M. Clermont and Theodore Eisenberg. They studied in a systematic way over a period of many years the rates of reversal by federal appellate courts of all federal civil decisions. You can find their law review article reporting on their findings here.
The bottom line? "Defendants have a substantial advantage over plaintiffs on appeal." Here are some of the highlights (or lowlights) of the study.
--"Defendants that appeal their losses after trial obtain reversals at a 33% rate, while losing plaintiffs succeed in only 12% of their appeals from trials."
--"Defendants that appealed their losses after trial obtained reversals at a 28% rate, while losing plaintiffs succeeded in only 15% of their appeals, with the spread increasing to 31% and 13% for appeals from jury trials."
--"[T]he defendants’ advantage grew as the case better fit the format of little victim against big defendant, just as it grew when the case has been decided by a jury."
--The biggest disparity between plaintiffs and defendants on appeal was in civil rights actions. "In these cases, plaintiffs obtain appellate reversals of trial wins by defendants in less than 6% of their appeals. In contrast, defendants obtain appellate reversals in nearly 44% of their appeals." That is nothing short of astonishing: ". . . prisoners have less difficulty maintaining their trial victories than do nonprisoner civil rights plaintiffs."
Professors Clermont and Eisenberg conclude that: ". . . the defendants’ higher reversal rate stems from real but hitherto unappreciated attitudinal differences between appellate and trial courts. These differences are probably owing to the appellate judges’ misperceptions regarding the trial level treatment of plaintiffs. The appellate judges seem to act on their perceptions of the trial courts’ being pro-plaintiff. That tendency would be appropriate if the trial courts were in fact biased in favor of the plaintiff. As empirical evidence has accumulated refuting a trial court bias, however, the appellate judges’ perceptions increasingly appear to be misperceptions. If misperceptions are in play, then this appellate leaning in favor of the defendant is a cause for concern."
It's about as fascinating a law review article as you're likely to read. A low bar to be sure, but still, it's something!