In Smalis et al. v. Pennsylvania, the U.S. Supreme Court ruled in 1985 that a state's post-acquittal appeal of a trial court's decision is barred by the Double Jeopardy Clause of the Fifth Amendment to the United States Constitution, which prohibits anyone from being prosecuted twice for substantially the same crime. The case involved two defendants who were acquitted by a judge on murder charges but found guilty on lesser offenses related to arson and conspiracy at their non-jury trial in Pennsylvania state court. The prosecution appealed against this acquittal arguing that it was based on an erroneous interpretation of law regarding what constitutes malice aforethought necessary for murder conviction under Pennsylvania law; however, they did not seek retrial or reconviction on murder charges if successful with their appeal but only correction of legal error made by trial judge while interpreting relevant laws during his judgment.

In the dissenting opinion for Smalis et al. v. Pennsylvania, Justice White disagreed with the majority's interpretation of the Double Jeopardy Clause in relation to pretrial appeals by prosecutors. He argued that a defendant is not truly "at risk" until a jury has been sworn and evidence presented at trial, thus an appeal before this point does not constitute double jeopardy. Furthermore, he contended that allowing such appeals could prevent unnecessary trials if errors were found in lower court rulings dismissing charges or reducing them to lesser offenses. Finally, he expressed concern about potential abuse of this ruling by defendants seeking dismissal on technical grounds knowing they cannot be retried even if their claims are later overturned on appeal.