<center><span class="news-text_italic-underline">García Armas and García Gruber v Venezuela (Appeal No 24-21.876) and Vietnam v Dangelas et al (Appeal No 24-10.445)</span> — First Civil Chamber, French Court of Cassation, 6 May 2026</center>
The first judgment arose from the long-running dispute between Venezuela and Serafín García Armas and Karina García Gruber, Spanish-Venezuelan dual nationals appearing before the Court of Cassation (“<span class="news-text_medium">COC</span>”) for the third time. Venezuela argued that general rules of public international law, in particular those governing diplomatic protection, should fill the bilateral investment treaty's (“<span class="news-text_medium">BIT</span>”) silence on dual nationality.
The COC rejected that argument. Where clearly drafted provisions define the scope of a BIT, which constitutes special law (lex specialis) as between the contracting states, other rules of public international law cannot be invoked to supplement the treaty's silence on dual nationality unless the contracting states' intention to that effect is established. Where the treaty itself says nothing on the matter, the jurisdictional protection afforded by the BIT extends to investors holding the nationality of both contracting states, without further condition.
The COC observed that the requirement for an investor's dominant and effective nationality not to be that of the respondent state, a concept well established in diplomatic protection, does not carry equivalent weight in investment treaty arbitration, a field whose contours are defined by the bilateral treaty itself. It is noteworthy that this conclusion diverges from the position taken by the Swiss Supreme Court on the same Spain-Venezuela BIT, lending particular significance to the French court's reasoning.
The second judgment applies the very reservation identified in the first. In a dispute between Vietnam and a dual US-Vietnamese national and her US-incorporated companies, the COC set aside the Paris Court of Appeal's (“<span class="news-text_medium">CA</span>”) judgment of September 2023, which had dismissed Vietnam's application to annul an UNCITRAL jurisdictional award. The CA had found that the applicable BIT contained no provision on dual nationality and had dismissed a diplomatic note issued in April 2023 by the United States Embassy in Hanoi as a mere opinion carrying no interpretive authority.
The COC disagreed. Under Article 31(3)(a) of the <span class="news-text_italic-underline">Vienna Convention on the Law of Treaties</span> (“<span class="news-text_medium">VCLT</span>”), a court must take into account any subsequent agreement between the parties regarding the interpretation or application of a treaty. The COC found that the diplomatic note, whose authenticity was uncontested, constituted precisely such a subsequent agreement, making jurisdictional access conditional on the investor's dominant and effective nationality not being that of the respondent state. The matter was remitted to a differently constituted bench of the CA.
Read together, the two decisions establish a coherent framework: BIT silence on dual nationality is not a lacuna to be remedied by reference to general international law. States wishing to restrict jurisdictional access for dual nationals must do so either expressly in the treaty text or through a subsequent agreement meeting the threshold of Article 31(3)(a) VCLT. Practitioners advising investors with dual nationality, or states assessing their treaty exposure, should examine both the treaty text and any diplomatic correspondence that may qualify as a subsequent interpretive agreement in the sense recognised by the COC.
