Arbitrary, capricious and unreasonable

In law, the standard of review is the amount of deference given by one court (or some other appellate tribunal) in reviewing a decision of a lower court or tribunal. A low standard of review means that the decision under review will be varied or overturned if the reviewing court considers there is any error at all in the lower court's decision. A high standard of review means that deference is accorded to the decision under review, so that it will not be disturbed just because the reviewing court might have decided the matter differently; it will be varied only if the higher court considers the decision to have obvious error. The standard of review may be set by statute, rule or precedent. In the United States, "standard of review" also has a separate meaning concerning the level of deference the judiciary gives to Congress when ruling on the constitutionality of legislation.

In the United States, the term "standard of review" has several different meanings in different contexts and thus there are several standards of review on appeal used in federal courts depending on the nature of the question being appealed and the body that made the decision.

In administrative law, a government agency's resolution of a question of fact, when decided pursuant to an informal rulemaking under the Administrative Procedure Act (APA), is reviewed on the arbitrary and capricious standard. Arbitrary and capricious is a legal ruling wherein an appellate court determines that a previous ruling is invalid because it was made on unreasonable grounds or without any proper consideration of circumstances. This is an extremely deferential standard.

A finding of fact made by a jury or an administrative agency in the context of APA adjudication or formal rulemaking will be normally upheld on appeal unless it is unsupported by "substantial evidence." This means something "more than a mere scintilla" of evidence. It means such relevant evidence as a reasonable mind might accept as adequate to support a conclusion." Under the "substantial evidence" standard, appellate review extends to whether there is any relevant evidence in the record which reasonably supports every material fact (that is, material in the sense of establishing an essential element of a claim or defense). Appellate courts will not reverse such findings of fact unless they have no reasonable basis in the evidence submitted by the parties. In other words, they will not reverse unless no one submitted any testimony, documentation, or other evidence which directly or indirectly (i.e., through reasonable inferences) supports a material fact, thereby implying that the finder of fact must have engaged in impermissible speculation with no reasonable basis in order to reach a verdict. If the parties presented conflicting evidence, appellate courts applying a "substantial evidence" standard assume that the jury or administrative agency resolved the conflict in favor of the prevailing party, and in turn, appellate courts must defer to such implicit findings about which side's witnesses or documents were more believable, even if they suspect they might have ruled differently if hearing the evidence themselves in the first instance. This is a highly deferential standard.

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