Turning to the reliance on the inability of a subordinate legislature to legislate for acts to be carried out outside the territory within the jurisdiction of that legislature, it has to be borne in mind that the foreign and external affairs affecting Guernsey are and have to be conducted by the Government of the United Kingdom, and legislated for by the UK Parliament and not by the States of Guernsey. It is common ground that in external affairs including defence and extradition Guernsey falls under the umbrella of United Kingdom actions and legislation. Accordingly, it was argued by Mr. Barnes and Mr. Harris, the States of Guernsey has no jurisdiction to legislate for the process of responding to foreign requests for assistance in obtaining evidence for criminal prosecutions. That is for the government and parliament of the United Kingdom. If the Investigation Law of 1991 is to be interpreted as legislating for such process, it is outside the powers of the States of Guernsey and void, at least to that extent.

The extra-territorial limitation on the powers of a subordinate legislature, though at times during the last 150 years a matter of controversy, was clearly recognised and provided for by the United Kingdom parliament when enacting the European Communities Act 1972 ("the 1972 Act"). Section 2 of the 1972 Act provides for the implementation of the European Treaties section 2(6) provides (inter alia) that a law passed by the legislature of Guernsey, Jersey or the Isle of Man,

"if expressed to be passed or made in the implementation of the Treaties or of the obligations of the United Kingdom thereunder, shall not be void or inoperative by reason of any inconsistency with or repugnancy to an Act of Parliament, passed or to be passed, that extends to the Island ... or any provision having the force and effect of an Act there (but not including this section), nor by reason of it having some operation outside the Island …; and any such Act or provision that extends to the Island ... shall be construed and have effect subject to the provisions of any such law." (references to Gibraltar have been omitted: the underlining is ours)