Are too few convictions overturned?
There is room for argument over whether the Criminal Cases Review Commission (CCRC) is too cautious in referring suspected miscarriages of justice to the Court of Appeal, as the Commons Justice Committee has said.
Certainly, the increased funding the committee has also recommended would make it easier for the CCRC to do its job.
But, as the Commons committee acknowledges, there is no point in referring more cases if the appeal judges are simply going to throw them out.
So the question at the heart of the MPs' report is whether we should change the grounds on which a conviction may be quashed.
And that, as the committee says, should be a matter for the Law Commission, which advises the government on reform of the law.
At present, the only ground on which appeal judges in England and Wales can overturn a conviction is that they think it is "unsafe".
A former lord chief justice said in 2002 that this did not allow appeal judges to "usurp the role of the jury as the body charged by law to resolve issues of fact and determine guilt".
Reluctance to overturn
Some critics argue that appeal judges should be more willing to overturn convictions if there is a "lurking doubt" about the case.
They say the Court of Appeal attaches too much weight to the verdict of the jury - which is only as good as the evidence it receives.
What is the Criminal Cases Review Commission?
- an independent public body established in March 1997 by the Criminal Appeal Act 1995
- its purpose is to review possible miscarriages of justice in the criminal courts of England, Wales and Northern Ireland and refer appropriate cases to the appeal courts
- based in Birmingham and has about 90 staff, including a core of about 50 caseworkers supported by administrative staff
- there are 11 commissioners, who work with the senior management team
- independent and impartial and does not represent the prosecution or the defence
Supporters of the present system fear that public confidence in jury trial would be undermined if appeal judges were more willing to overturn jury verdicts.
Critics respond that Parliament undermined confidence in juries when it created the Court of Criminal Appeal (as it was then called) in 1907.
Public confidence is more likely to be undermined, they add, if wrongful convictions go uncorrected.
Senior judges were unwilling to debate the law with MPs.
But their thinking is revealed in written evidence by Lord Judge, the former lord chief justice.
He said his successor, Lord Thomas of Cwmgiedd, agreed with it.
Lord Judge recalled a witness appearing before him who had once given "beautifully crafted evidence" and then "spoiled the impact by blushing each time he told a lie".
The former chief justice pointed out that neither the CCRC nor the Court of Appeal had the advantage of seeing witnesses and observing their body language in the way that a jury had.
"That advantage cannot be ignored or overlooked," Lord Judge said, "and must be taken into account in any analysis of the safety of the conviction."
There were many cases in which juries had to decide whether it was the complainant or the defendant who was lying. Appeal judges simply could not tell this by reading a written transcript of the evidence.
Even so, Lord Judge insisted, the verdict would be quashed if the appeal court was left in doubt about the safety of a conviction.
Doubts about verdict
At present, cases are referred if the CCRC thinks there is a "real possibility" the conviction will be overturned because of new evidence or arguments.
Lord Judge dismissed a suggestion the CCRC should go further and announce it had doubts about a jury's verdict.
If the appeal court disagreed, there would then be two conflicting decisions by public bodies.
But the former chief justice did say the CCRC could refer a case to the Court of Appeal "on the basis that there is a real possibility that the verdict of the jury is against the weight of the evidence".
The CCRC has welcomed the suggestion the Law Commission should look at this again.
But rewording the "unsafe" test is not likely to make much difference.
In the end, it all boils down to deciding who was telling the truth.