Constitutional law – Foreign sovereign state. The parties had been engaged in arbitration and the claimants issued an arbitration claim form to seek to enforce the defendant's compliance with the tribunal's order. The claimants obtained the court's permission to serve the claim form on the defendant's solicitors and a further order for an expedited timetable for the determination of the arbitration claim and an abridgement of the time for filing an acknowledgement of service. The Commercial Court granted the defendant's application to set those orders aside. Section 12(1) of the State Immunity Act 1978 had applied as, under that section, the issue of an arbitration claim form constituted the institution of proceedings. Further, there had been no, or no operative, agreement as to the manner of service under s 12(6) of the Act. Finally, the defendant had not, in the circumstances, waived its right to rely on s 12 of the Act.