Abuse of discretion
"Abuse of discretion" is a legal standard used by appellate courts in reviewing many types of decisions made by trial courts,typically decisions on matters of equity. This standard is highly deferential in presuming that the trial court acted correctly. This standard creates a very high threshold for an appellant to surmount to overturn a trial decision. The onset of the hard look doctrine has made the standard slightly less deferential, though. See, e.g. Citizens to Preserve Overton Park.
Note, however, that "[a] district court by definition abuses its discretion when it makes an error of law." Koon v. United States, 518 U.S. 81, 100 (1996). "[T]he abuse-of-discretion standard includes review to determine that the discretion was not guided by erroneous legal conclusions." Koon, 518 U.S. at 100.