I'm not sure I can be very helpful on that. I believe that there have been individual rulings as to the breadth of disclosure that have gone further than I might have, if I were making the rulings. But by the same token, I would be reluctant.... I guess I just don't know enough about how this practice might be curtailed.
My own view is that I would find that rarely is it relevant, and therefore it's not disclosable. Nevertheless, there may be a case where some particular aspect of it is going to be relevant, and then it should come in. I was going to use an analogy, of DNA and how the DNA system operates. Clearly, that has to be something that can be explored—or the system of handling evidence. But investigative techniques...? Clearly there's a recognized privilege of informer; that is a long-recognized privilege, and the courts, as far as I know, never have any hesitation in applying it.
If I were a judge I would be looking at asking first of all whether it is irrelevant, and then second of all, whether it would come into.... The informer is privileged and protected not only to protect the informer but to some extent to protect the method that is used. I have presided on many cases in which there have been many undercover police officers who have done a lot of the work in the case and I haven't seen a particular problem, but I know there can be some, and I don't have an answer as to how you deal with them.