Penologists tell us that imprisonment serves four purposes: retribution, deterrence, reformation, and protecting the public by isolating the criminal.

From this they conclude that custodial sentences for most non-violent offences serve no purpose.

This includes the ostentatious prison terms handed out for financial crimes, such as the three year sentence given to the actor Wesley Snipes for tax evasion.

As retribution, it is excessive. As deterrence, it is less effective than clear financial penalties. As reformation, it is counter-productive because three years among hardened criminals is unlikely to make anyone a better man. As public protection, it is unnecessary because Mr Snipes poses no threat to the public that demands he be isolated from the mainstream population.

Sound business sense dictates he is more valuable as an active economic unit, working to pay financial penalties, than as an expensive ward of the state.

As for preventing tax evasion, the best strategy would be a clear and simple system that leaves little room for it, and rates set at a level so low that it becomes pointless.