In all cases referred for a charging decision, the CPS should use whichever offence, including treason, is appropriate to the facts of the case. However, modern criminal offences, including terrorism offences, usually offer a better chance of a successful conviction than would a prosecution for treason.
British jihadists who go abroad to support ISIS are aiding and abetting the Queen’s enemies, and now that we have the horrific spectacle of British citizens beheading other British citizens and citizens of allies on international television, should it not be made clear to these people that it is worse than murder and terrorism—it is treason—and that should they ever be apprehended they should be prosecuted for such?
I have a good deal of sympathy with what my hon. Friend says. The point I would make is a purely practical one. I think it important that treason remains available to prosecutors in appropriate cases and I wish to see that continue, but I also think it important to recognise that there are specific practical difficulties in the prosecution of treason—whether it be the establishing of the direct or constructive levying of a war under one limb of the offence or indeed defining the sovereign’s enemies under the other. It is important that we prosecute effectively.