When the dust has settled a bit on the aftermath of the English riots, I hope someone will do a study of the sentences passed on offenders – and on the pointers they may give to penal policy on both sides of the border.

With news today that the prison population in England & Wales is rising by over 100 a day as the courts process the cases, now standing at a new high of over 86,000, only about 1,400 short of "usable operational capacity", we should pause to reflect on what would happen if courts adopted more generally the hardline approach seen recently.

Put bluntly, the system would quickly break down. How could we cope with any more custodial sentences than are now being passed? And at what cost to the public purse?

That is not to suggest that those who caused the recent disorder should be leniently dealt with, more especially those who turn out to have had reasonable jobs but who for whatever reason decided to join in the lawlessness. Sure, it would be good if means could be found to make them atone to the communities who have suffered from their actions, but it is no doubt impractical to deal with large numbers in this way, and some of the offences involved were very serious. So the system has to have the capacity to cope with a large scale emergency such as the present, which makes it all the more important that in normal circumstances it is managed – i.e.offenders are dealt with – on some basis other than simply locking people up, unless there is little prospect of an alternative disposal doing any good (or the offence is simply too grave).

Meantime we also need a sense of proportion, and of comparative justice, being applied to the rioting cases, so that someone sentenced (say) for receiving stolen goods is not dealt with as if they were guilty of public disorder in addition. And while these events, and the ways of dealing with them, should (indeed need to) be the subject of political debate, the temptation for politicians to steer the courts towards a particular sentencing approach has to be resisted.

For Scotland, figures published today show for once a small reduction last year in the average prison population – but come with a warning that with more long sentences having been passed in recent years, the trend remains relentlessly upwards. If society thinks these sentences are needed, society also has to be prepared to face the financial cost. All the more important too, to provide the resources to make community disposals effective, so they can do some good in their own right at the same time as ensuring that prison places are available in cases where there is no alternative.