Joshua Rozenberg is ready to support ‘reasons of state’ for restricting the right to ask a magistrate to authorise the first step in the private prosecution of a suspected war criminal.

Our experts in the House of Lords may have produced persuasive legal arguments in support of this proposed change, as Mr Rozenberg maintains, but he fails to make clear that these are ultimately political judgments - by unelected persons - not legal judgments at all.

Better, he implies, for the ‘war on terrorism’ - whatever that means - to be enhanced than the arrest of suspect individuals temporarily within the UK in a process in which a full prosecution is probably unlikely to succeed.

There is however a persuasive view that the traditional practice of having to demonstrate an arguable case before a magistrate rather than, as now proposed, the DPP, roots justice in the community and should not be abandoned except in the gravest of circumstances.

There is also the legal principle of Fiat justitia ruat caelum - justice should prevail even if heaven collapses.

To Mr Rozenberg, this might be pie in the sky: it is true General Pinochet ultimately escaped from the UK jurisdiction, to the great relief of supporters of ‘reasons of state’, but it did look for a time as if justice was actually going to be done.

Roger Sceats, DR Sceats, Surbiton, Surrey