Establish a government-approved version of Islam
   This extraordinary proposal was made across party lines by the MPs Hazel Blears and Dr Julian Lewis, who insist that "the government must sponsor a particular interpretation of Islam" (The Times, August 27). While Theresa May is capable of many things, rewriting the Koran "to develop a tolerant vision of Islam" (perhaps with Prince Charles as "defender of the faith") might be a task too far.

Resuscitate the Treason Act, 1361
   David Davis MP, of all people, has called for jihadists to be prosecuted as traitors. The Treason Act was last promoted by Lord Hailsham, in his dotage, for IRA suspects, replete with the death penalty (well, it would have silenced the Birmingham Six and the Guildford Four). Hanging for treason was only abolished in 1999 (because treason includes "adultery with the King's son and heir" and there was concern that James Hewitt's guilt would render Diana, as his accomplice, a notional candidate for the gallows).

This obsolete 1361 law now provides life imprisonment for men who "levy war against our Lord the King in his realm, or give the King's enemies comfort elsewhere". It only remains on the statute books because of the laziness of law reform and our nostalgia for history. It is precisely that nostalgia which should deter us from treating vicious IS killers on a par with Sir Roger Casement, Anne Boleyn and Sir Walter Raleigh. Besides, the archaic language is now open to endless legal arguments — William Joyce ("Lord Haw-Haw") was scandalously hanged in 1946 before the Law Lords delivered their reasons, when it turned out that one judge (who was undoubtedly correct) had changed his mind and decided that Joyce was innocent because he had been born in America. Now, as the 1361 Act must be interpreted in conformity with the 1998 Human Rights Act, any treason conviction would be subject to endless legal arguments, to Strasbourg and beyond.

Bring back the death penalty
   Remarkably, a call not heard over the summer, other than from talk radio and the wilder shores of UKIP. Those most enthusiastic for the return of the gallows dare not say so: they are, of course, the fighters of IS, who would relish this guaranteed pathway to paradise. They would all be likely to return from the killing fields of Syria and Iraq to die at the hands of an infidel hangman: this, they believe, is the most glorious way to go.

Before Parliament considers any of these well-intentioned but impractical ideas for new offences and new ways of internment without trial, it would be sensible to ask exactly what crimes against British law IS fighters have committed, and how they can be appropriately charged, tried and punished.

IS is not a state (even if it fantasises that it has become a caliphate). It comprises a growing group of international criminals bent on killing Christians, Shia Muslims and members of other religions, torturing civilians, and executing opponents (and hostages) without trial. IS fighters are, so to speak, the pirates of the desert — hostis humanis generis, the enemies of all humankind. They appear to be guilty of an array of international crimes — war crimes, crimes against humanity and (arguably) even genocide.