The fact remains however that, as the Court has already observed, the United States has declared (letter from the Permanent Representative, 11 March 1988) that its measures against the PLO Observer Mission were taken “irrespective of any obligations the United States may have under the [Headquarters] Agreement”. If it were necessary to interpret that statement as intended to refer not only to the substantive obligations laid down in, for example, sections 11, 12 and 13, but also to the obligation to arbitrate provided for in section 21, this conclusion would remain intact. It would be sufficient to recall the fundamental principle of international law that international law prevails over domestic law
. This principle was endorsed by judicial decision as long ago as the arbitral award of 14 September 1872 in the Alabama
case between Great Britain and the United States, and has frequently been recalled since, for example in the case concerning the Greco-Bulgarian “Communities”
in which the Permanent Court of International Justice laid it down that
“it is a generally accepted principle of international law that in the relations between Powers who are contracting Parties to a treaty, the provisions of municipal law cannot prevail over those of the treaty (P.C.I.J., Series B, No. 17, p. 32).