In Buck v. Attorney General  Ch 246, the claimant challenged the validity of an order in council giving effect to the Sierra Leone Independence Act 1961. The order used general enabling words, not expressly stating which power had been used for their creation. Wilberforce J. held that the result of those general enabling words was that the order was made under a power conferred by the British Settlements Act 1887 even though that order did not expressly refer to that power. As a result the order was valid.
In Buck v. Attorney General  Ch 745, claimant appealed this decision by an action for declaratory relief. The appeal failed. It was held that as a matter of international comity an English court should not grant declarations which would amount to an unwarranted interference in the affairs of an independent member of the British Commonwealth. In proceedings for declarations brought against the Attorney General of England the court has no jurisdiction to make declarations as to the validity of the constitution of an independent sovereign state, in this case Sierra Leone.
“These courts cannot, in my view, make a declaration impugning the validity of the constitution of a foreign or independent state, at any rate where that is the object of the action. This may be put as a matter of international comity, or upon the ground of effectiveness. No relief effective in this country or anywhere else is sought by the action. Any declaration which the court might make may be ignored with impunity by the independent country into whose affairs it pretends to pry, and I am of opinion that it would be not only improper, but contrary to law in those circumstances to make such a declaration as is here sought.”
“As a member of the family of nations, the Government of the United Kingdom (of which this court forms part of the judicial branch) observes the rules of comity, videlicet, the accepted rules of mutual conduct as between state and state which each state adopts in relation to other states to adopt in relation to itself. One of those rules is that it does not purport to exercise jurisdiction over the internal affairs of any other independent state, or to apply measures of coercion to it or to its property, except in accordance with the rules of public international law. One of the commonest applications of this rule by the judicial branch of the United Kingdom Government is the well-known doctrine of sovereign immunity. A foreign state cannot be impleaded in the English courts without its consent: see Duff Development Co. v. Kelantan Government. As was made clear in Rahimtoola v. Nizam of Hyderabad, the application of the doctrine of sovereign immunity does not depend upon the persons between whom the issue is joined, but upon the subject-matter of the issue. For the English court to pronounce upon the validity of a law of a foreign sovereign state within its own territory so that the validity of that law became the res of the res judicata in the suit, would be to assert jurisdiction over the internal affairs of that state. That would be a breach of the rules of comity’ and ‘The only subject-matter of this appeal is an issue as to the validity of a law of a foreign independent sovereign state, in fact, the basic law containing its constitution. The validity of this law does not come in question incidentally in proceedings in which the High Court has undoubted jurisdiction, as, for instance, the validity of a foreign law might come in question incidentally in an action upon a contract to be performed abroad. The validity of the foreign law is what this appeal is about; it is about nothing else. This is the subject-matter over which the English courts, in my view, have no jurisdiction.”
Diplock LJ continued:
“Mr. Gardner [for the plaintiffs] urges, however, that there was a moment of time when the Order in Council purported to be in force before Sierra Leone became an independent sovereign state, while the Government of the United Kingdom was still the sovereign government of the colony of Sierra Leone. He submits that, during that period, the English court would have had jurisdiction to declare the Order in Council to be ultra vires, and that it does not lose that jurisdiction merely because Sierra Leone has subsequently become a foreign sovereign state.
I should in any event reject this argument. In applying the rules of comity, one looks to the substance of the issue, not to its form. The Order in Council was, on the face of it, intended to provide the constitution not of the colony of Sierra Leone, but of the new independent foreign state. The issue as to the validity of the Order in Council was thus, in substance, at the date of the writ, an issue as to the validity of the constitution of an independent sovereign state. But there is, I think, a technical answer also. As soon as Sierra Leone became independent, the Order in Council ceased to have any effect as an Order in Council, that is, as an exercise of the sovereign power of the United Kingdom Government represented by the Attorney-General of England. Whatever effect it then had was as part of the law of a foreign sovereign state, into the validity of which this court has no jurisdiction to enquire.”