There is no mystery in the language which courts from time immemorial expressed in an attempt to explain when they will interfere with a verdict which has been challenged on the grounds of either excessiveness or inadequacy. Lip service is given to the rule that the size of the verdict alone is not the criteria for interference with the verdict of a jury. The usual language is that excessiveness or inadequacy, to warrant interference, must evince or carry an implication of passion or prejudice, corruption, partiality, improper influences, or the like. An analysis of the decisions, however, justifies "the conclusion that courts generally grant relief if convinced that the verdict substantially exceeds or falls below any rational appraisal or estimate of the damages, even though the inference of passion, prejudice, partiality, or other improper notice on the part of the jury is no more natural or reasonable than the inference of a mistake or misapprehension" on the part of the jury.
Owen T. Palmer Jr., Inadequate Damages in P.I. Actions: Trends in Appellate Decisions, 17 Clev.-Marshall L. Rev. 413 (1968)