Malcolm Rifkind in this FT article makes the specific and obvious case related to prisons but, in the background, is a general debateable case against privatisation of what we regard as public services. For example, monarchies have often used foreign mercenaries to fight wars or impose control, so there is no clear historical distinction to be made between soldiers and prison officers. It comes down, in democratic systems, to what is acceptable to the electorate. The current debate about bailiffs is also symptomatic of this problem. There is actually no logical line which can be drawn. Taxes could be levied and collected by private companies instead of HMRC, just as the Proceeds of Crime are currently collected by Rossendales. Prison vans could be driven by prison or court employees us rather than GEO Amey etcetera. It is, actually, just a question of what the electorate and its representatives will put up with. As criminals are, by definition, a minority, democracy allows itself the pleasure of privatising anything concerning them until it is shown to be financially inefficient, does not produce the outcome that was expected or until our representatives feel that moral boundaries have been crossed on which the electorate could not be expected to adjudicate.