I’ve been doing a fair bit of that recently. For anyone interested, Bruce Fein and I gave it a go at Cato a few months back, now pub’d in the Cato Policy Report for Sept/Oct 2007 (beginning on p. 13). I also appeared on a panel about FBI National Security Letters with several experts (including the Bureau’s general counsel, Valerie Caproni), now available in the ABA Standing Committee on Law & National Security’s August 2007 Report (beginning on p. 4).