Court of Criminal Appeal
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.
Following the Criminal Appeal (Scotland) Act 1926 (16 & 17 Geo. V), when the Scottish High Court of Justiciary hears criminal appeals, it is known as the Court of Criminal Appeal. The Criminal Appeal (Scotland) Act 1927 was passed the following year specifically to deal with the Case of Oscar Slater.
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. 
England and Wales
The Court of Criminal Appeal was an English appellate court for criminal cases established by the Criminal Appeal Act 1907. It superseded the Court for Crown Cases Reserved to which referral had been solely discretionary and which could only consider points of law. Throughout the nineteenth century, there had been opposition from lawyers, judges and the Home Office against such an appeal court with collateral right of appeal. However, disquiet over the convictions of Adolf Beck and George Edalji led to the concession of a new court that could hear matters of law, fact or mixed law and fact.
Though the court was staffed with the judges who had shown such hostility (consisting of the Lord Chief Justice and eight judges of the Queen's Bench Division of the High Court), it had a 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 simultaneously 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.