Is it appropriate for domestic courts to use the margin of appreciation?

Right now, I'm working on some online revisions for my book on administrative law. While doing so, I stumbled upon R (S) v. Secretary of State for Justice EWHC 1810 (Admin), where Sales J. makes some intriguing (albeit perhaps controversial) observations regarding the doctrine of margin of appreciation.

The main issues in the case were Rule 31A of the Prison Rules and Section 1(3) of the Prisoners' Earnings Act of 1996. When these rules were combined, prison governors could tax convicts up to 40% of their earnings from labor they did outside of jail, provided that the earnings were more than a set sum. Victim Support received the funds that were collected. Governors received Prison Service Instructions acknowledging that they had the option to impose a tax, but the government anticipated levies to be implemented absent extraordinary circumstances. For this purpose, the Government's definition of extraordinary circumstances was outlined in the Instructions.

In this instance, it was claimed that the Instructions were illegal because they obliged governors to act in a way that would violate Article 1, Protocol 1 of the European Convention on Human Rights, or that they anticipated doing so. Sales J ruled (at [45]) that "it is well within the national authorities' margin of appreciation, in line with these authorities, to impose a special tax upon prisoners in receipt of enhanced earnings for the purposes of securing hypothecated funding to support the victims of crime in the present case."

Sales J disagreed with such claim. He noted that the rights specified in the Convention "as it has effect for the time being in relation to the United Kingdom" are the "Convention rights" to which the Human Rights Act 1998 grants effect in UK law (per section 1(1) of that Act). "That effect is determined, in part, by operation of the margin of appreciation applied by the ECtHR in determining whether there has been any violation of Convention rights," said Sales J. (at [53]).

But do Laws LJ and Sales J actually have the same agenda? Laws LJ contends that the domestic doctrine of margin of discretion or deference and the transnational doctrine of margin of appreciation are related, but he does not suggest that they are the same. This is due, in part, to the fact that one of the justifications for the transnational doctrine—the "relative disadvantage suffered by the international court"—does not apply to domestic courts. Conversely, Sales J contends that the whole margin of appreciation is hardwired into the "Convention rights," meaning that a domestic court interpreting such rights would be forced to provide Parliament or the Executive the

Although I think Sales J's reasoning makes sense, I'm not sure if I agree that it gets him to the proper answer. However, I believe that his opinion on the margin of appreciation (and how domestic courts can apply it) is closely related to his more general perspective on the relationship between domestic courts' application of the Convention and the Strasbourg Court's application of the Convention; for more on this, see his recent paper, "Strasbourg jurisprudence and the Human Rights Act: a response to Lord Irvine" [2012] Public Law 253.