A former administrative employee of the Saudi Embassy brought discrimination and harassment claims. The Supreme Court held the Court of Appeal erred by dismissing the Embassy’s immunity appeal without considering its duty under section 1(2) of the State Immunity Act 1978, but ultimately found no immunity applied given the employee’s purely administrative role.
Background
Mrs Antoinette Costantine, a dual Lebanese-British national and Catholic Christian, was employed by the Royal Embassy of Saudi Arabia (Cultural Bureau) from January 2010 until January 2018. She worked in various capacities: initially as a Post Room Clerk undertaking data entry tasks relating to university invoices, then as Secretary to the Head of the Cultural Affairs Department performing basic administrative functions (answering telephones, booking rooms, arranging catering), and finally returned to the post room where she undertook little or no work before her employment was terminated.
Mrs Costantine brought claims in the Employment Tribunal for direct discrimination and harassment on grounds of religious belief under the Equality Act 2010. The Embassy asserted State immunity under the State Immunity Act 1978 (“SIA 1978”). At a preliminary hearing on 29 June 2021, Employment Judge Brown made detailed findings of fact about the respondent’s duties and concluded that State immunity did not apply because the respondent’s role was purely administrative and ancillary, not sufficiently proximate to the governmental functions of the mission.
The Embassy’s appeal to the Employment Appeal Tribunal was rejected on the sift and a subsequent rule 3(10) application was dismissed. Permission to appeal to the Court of Appeal was granted by Bean LJ, who noted the general importance of the immunity issue. However, before the appeal hearing, the Embassy’s solicitors withdrew due to non-payment of fees. The Embassy did not attend the hearing on 13 March 2024, and the Court of Appeal dismissed the appeal for non-appearance without substantively considering the immunity question.
The Issue(s)
Issue 1: The Court of Appeal’s duty under section 1(2) SIA 1978
Was the Court of Appeal under a duty to consider whether State immunity applied notwithstanding the appellant’s non-attendance at the hearing? If so, did it comply with that duty?
Issue 2: The correct test for State immunity
Did the Employment Tribunal apply the correct legal test for State immunity to the facts of the case?
Issue 3: Impact of the Remedial Order
What was the effect of the State Immunity Act 1978 (Remedial) Order 2023 on the applicable test?
The Court’s Reasoning
The section 1(2) duty extends to appellate courts
The Supreme Court unanimously held that the Court of Appeal was under a duty to consider the immunity question of its own motion. Lord Lloyd-Jones, delivering the sole judgment with which all other Justices agreed, emphasised the fundamental importance of State immunity as a mandatory rule of customary international law deriving from the sovereign equality of States. Section 1(2) of the SIA 1978 provides that a court “shall give effect to the immunity conferred by this section even though the State does not appear in the proceedings in question.”
Lord Lloyd-Jones reasoned that the statutory language was clear and general:
Section 1(2) is expressed in general terms. It uses mandatory language to impose a duty on ‘a court’. ‘Court’ is defined generously by section 22(1) of the SIA 1978 as including ‘any tribunal or body exercising judicial functions’. Nothing on the face of the statute excludes an appellate court from the section 1(2) duty.
He rejected the respondent’s submission that the duty did not extend to appellate courts, finding that such an exclusion would defeat the very purpose of the provision:
Consider, for example, a case in which a defendant State does not appear at the hearing before the court of first instance which considers the question of immunity but, on grounds which are clearly erroneous, denies immunity. If the matter subsequently comes before an appellate court, the appellate court should certainly be under a duty to consider of its own motion whether the State was entitled to immunity and whether the decision below was correct.
The Court traced this duty back to the common law, citing Kay LJ in Mighell v Sultan of Johore [1894] 1 QB 149:
I think that the Court itself would be bound to take notice of the fact that it had no jurisdiction.
Lord Lloyd-Jones concluded that the Court of Appeal erred in law by dismissing the appeal without substantively addressing the immunity question:
The failure of the appellant to appear at the hearing of its appeal before the Court of Appeal on 13 March 2024 was regrettable and resulted in a waste of that court’s time. Nevertheless, in the circumstances of this case the Court of Appeal was not entitled simply to dismiss the appeal, as it did, without first considering of its own motion whether the appellant was entitled to State immunity.
The Employment Tribunal applied the correct test
Turning to the substantive immunity question, Lord Lloyd-Jones applied the framework established by the Supreme Court in Benkharbouche v Embassy of the Republic of Sudan [2017] UKSC 62. Under both the principles in Benkharbouche and the new section 16(1)(aa) inserted by the Remedial Order, immunity applies to non-diplomatic mission staff only where either (i) the State entered into the contract of employment in the exercise of sovereign authority, or (ii) the State engaged in the conduct complained of in the exercise of sovereign authority.
As to the first limb, Lord Lloyd-Jones cited Lord Sumption’s analysis in Benkharbouche:
The role of technical and administrative staff is by comparison essentially ancillary and supportive. It may well be that the employment of some of them might also be exercises of sovereign authority if their functions are sufficiently close to the governmental functions of the mission.
Employment Judge Brown had made unchallenged findings that: Mrs Costantine’s post room role was “in essence a data entry job”; she was unaware she could access confidential information and never did so; her secretarial functions were confined to routine administrative tasks; and she did not attend meetings, access her superior’s diary, or handle governmental correspondence. Lord Lloyd-Jones found no error of law in the Employment Tribunal’s application of the Benkharbouche test to these facts and was satisfied that the judge had correctly assessed the proximity of the respondent’s role to governmental functions.
As to the second limb, which the appellant sought to raise for the first time before the Supreme Court, Lord Lloyd-Jones allowed the argument to be heard given the policy underlying section 1(2) but found it without substance:
The appellant has produced no evidence to support the suggestion that the treatment of the respondent engaged the State’s sovereign interests. There has been no accusation of wrongdoing on the part of the respondent. There has been no disciplinary investigation against her. There has been no suggestion that her dismissal was connected in any way with sovereign matters such as State security. If the appellant were entitled to immunity in these circumstances, there would be such an entitlement in every case of dismissal of a member of the administrative staff of a mission.
The Remedial Order and its effect
The Court noted that the Remedial Order, which came into force on 23 February 2023, was intended to reflect the principles stated in Benkharbouche and customary international law. Furthermore, the respondent remained entitled to rely on Article 47 of the EU Charter to disapply any broader domestic immunity provisions, given that proceedings were commenced before IP completion day. In the result, the same test applied regardless of whether the pre- or post-Remedial Order regime governed any particular claim.
Practical Significance
This decision is significant in at least three respects. First, it establishes authoritatively that the duty under section 1(2) of the SIA 1978 to give effect to State immunity applies to all courts including appellate courts, and that this duty cannot be circumvented by procedural defaults on the part of the foreign State. Courts at every level must consider the immunity question of their own motion where it arises, even if the State does not appear.
Second, the case provides important guidance on the application of the Benkharbouche framework to the administrative and technical staff of diplomatic missions. The key question is whether an employee’s functions are sufficiently proximate to the governmental functions of the mission. Purely administrative and supportive roles — even within an embassy — will not attract immunity. The decision confirms that the test is fact-sensitive and turns on the actual duties performed rather than on the broad context of employment within a sovereign institution.
Third, the case confirms that the second limb of the immunity test — whether the State engaged in the conduct complained of in the exercise of sovereign authority — requires specific evidence linking the treatment of the employee to sovereign interests, such as State security or recruitment policy. Bare assertions that investigating a dismissal would require inquiry into sovereign decisions are insufficient.
Verdict: The appeal was dismissed. The Supreme Court held that the Court of Appeal erred in law by failing to consider of its own motion whether the appellant was entitled to State immunity under section 1(2) of the SIA 1978, but concluded that had it done so, it would necessarily have found no immunity applied. The Employment Tribunal had correctly applied the law and its findings that the respondent’s role was purely administrative and not sufficiently proximate to governmental functions were upheld.
Source: The Royal Embassy of Saudi Arabia (Cultural Bureau) v Costantine [2025] UKSC 9
