The attorney general, Lord Goldsmith, has been no slouch in exercising his power to refer sentences he regards as "unduly lenient" to the appeal court, with 698 cases referred since he took over the top law officer's job in 2001.

In 521, the court agreed, and 414 offenders had their sentences increased. Most of the cases are the most serious, involving violence, sex attacks, drugs or robberies, but it is not enough for the victim's family or the newspapers to claim that a judge had been "too soft" for the court of appeal to look at it again.

The rules for the attorney to make a reference are quite tough. An unduly lenient sentence must not be simply lenient. It must "fall outside the range of sentences which the judge, applying his mind to all the relevant factors, could reasonably consider appropriate".

The home secretary cannot refer cases to the court of appeal. John Reid can write to Lord Goldsmith, but only as a member of the public, and he should not be too surprised that his intervention is interpreted as political pressure on the attorney. Lord Goldsmith must consider the request within 28 days, and can only make reference on strict legal merits without implying any criticism of the judge. The difficulty now is that he appears to be under political pressure. The basic criteria were laid down by Lord Lane in 1989.

He said it had to be shown there was "some error of principle in the judge's sentence and that in the absence of the sentence being altered by the court public confidence would be damaged".

Such sentence reviews should be the exception and not become routine in borderline cases. The attorney also has to consider whether the appeal court is likely to increase the sentence and whether that would be in the public interest. On this basis, the home secretary's complaint that Craig Sweeney's minimum life sentence tariff of five years and 108 days did "not reflect the seriousness of the crime" does not sound like the "error of principle" Lord Lane envisaged. He seems instead to have just disagreed with Judge John Griffith Williams.

Lord Goldsmith's success last week in persuading the appeal court to increase the minimum term of the life sentence on the rapist of a baby from six to eight years illustrates the point. The appeal court ruled that the absence of any remorse in Alan Webster justified the higher term even though he - like Sweeney - got a one third discount for pleading guilty.