The Court of Criminal Appeal hears cases which have been appealed from the Circuit Court, Central Criminal Court and Special Criminal Court. It is made up of three judges and has a majority decision. Leave to appeal is only given where there is a disagreement on a point of law, although an exception can be made when new evidence becomes available which could not have been presented before the original court.
The court consists of at least three judges when hearing appeals against conviction and two when hearing appeals against sentence, although more judges may sit when the court is dealing with exceptionally difficult cases or those where important matters of law may be considered. This is known as a Full Bench. Appeals are heard from the High Court of Justiciary, the Sheriff Courts and the District Courts. The High Court also hears appeals in cases referred to it by the Scottish Criminal Cases Review Commission.
However, though the Court was staffed with the judges who had shown such hostility, it had a remarkably restraining effect on the excesses of prosecutors. During the period 1909-1912, there was an average of 450 annual applications for leave to appeal of which an average of 170 were granted. Of that 170, conviction was quashed in 20 percent of cases and sentence varied in another 22 per cent. Rulings of the Court included limitation of the lower courts' ability simultaneoulsy to try multiple defendants, multiple indictments and disparate counts within an indictment. The ability of the prosecution to introduce further evidence after the close of the prosecution case was curtailed as were several prejudicial practices with a defendant's previous criminal record. Further, trial judges' ability to invade the jury's role as trier of fact came under scrutiny, as did the practice of insisting that the defence proceed even in the case of an inadequate prima facie case by the prosecution. The Court also did much to refine and systematise the law of evidence.