From Shield to Reciprocity: Implied Consent and the Structural Evolution of Counterclaims in ISDS Reform

Can a dispute settlement system preserve its legitimacy if it structurally enables one party to assert claims while limiting the other’s ability to respond in kind? The UNCITRAL Working Group III (“WGIII”) on the reform of investor-State dispute settlement (“ISDS”) is now debating this issue of procedural reciprocity. Draft Provision 10 (“DP 10”) has been viewed in recent criticism as a technical solution to the persistent jurisdictional issues facing State counterclaims, with the 53rd session of WGIII (January 2026) marking an decisive step in refining the design of the Multilateral Instrument on ISDS Reform (“MIIR”).

Yet it appears from the negotiations that concluded in this session that DP 10 does more than just making counterclaims easier. It touches on the fundamental architecture of arbitral consent, which is based on investor access, historically uneven, and structurally unilateral. Inherently, DP 10 signals a reconfiguration of how consent functions inside ISDS. This post examines therefore how DP 10 reconfigures consent as a structural feature of ISDS procedure and what this means for procedural reciprocity.

Reconfiguration of Implied Consent : Estoppel as a Procedural Anchor ?

Consent in ISDS has historically operated as a unilateral gateway crystallized asymmetrically by jurisdiction after the investor accepts the State's offer. DP 10 attempts to recalibrate that model by integrating reciprocity into the procedural structure of the dispute. Hence, submitting a claim implies implicit consent (old Draft Provision 11, paras. 27 – 29) to counterclaims that are sufficiently related to the dispute. By doing this, it shifts the analytical focus from whether consent exists to the extent of reciprocal procedural engagement once arbitration has been initiated.

In that sense, the provision operates in a manner functionally analogous to estoppel: by seizing the tribunal, the investor cannot subsequently deny the tribunal’s jurisdiction over counterclaims that arise from the same legal and factual source. Therefore, DP 10 operationalizes accepting a specific area of procedural reciprocity as a necessity to activate the arbitral mechanism (DP, para. 47). As noted, this mechanism ensures that the “factual and legal connection” (DP, para. 45) between the primary claim and the counterclaim becomes the anchor of the tribunal’s jurisdiction, rather than a separate, explicit search for investor assent. Investors are not made into traditional subjects of international responsibility in this way. However, by incorporating a reciprocal element into the initiation process itself, it rebalances the arbitral consent equation.

By recognizing the start of arbitration as implied assent to related counterclaims, DP 10 intends to specifically address the structural asymmetry of ISDS (see Kappes v. Guatemala case), so long as there is a clear factual and legal connection (see para. 40). This shift is theoretically grounded in the Secretariat’s annotations (WP.254, para. 49), which frame the initiation of arbitration as the decisive act of procedural submission, provided there is a clear factual and legal connection. This link is usually incorporated into the factual pattern itself in areas like extractive industries, where environmental regulations and expropriation claims commonly interact. Due to asymmetrical consent design, DP 10 makes sure that these links are not omitted at the jurisdictional stage (DP, paras. 47 and 48).Hence, as clarified in DP 10 (para. 39), this connection is the key to ensuring that counterclaims do not expand the dispute beyond the scope of the investor's original consent (WP.253, DP 10, para. 1).

The threshold objection that investor consent is categorically lacking is one persistent jurisdictional barrier that is removed by DP 10, although it does not completely eliminate such caution. Thus, DP 10 is providing a predictable framework for tribunals that have handled the matter conservatively even in cases where counterclaims have been filed, which have perpetuated asymmetry in both treaty text and interpretive practice of ISDS (see Urbaser v. Argentina case). But while jurisdiction may be secured by DP 10, normative foundations of counterclaims remain the keystone of the transformation.

Indeed, the significance of DP 10 lies less in guaranteeing the success of counterclaims than in enabling tribunals to reach the substantive questions they raise. This distinction is important because many of the difficulties historically associated with counterclaims concern their legal basis and normative grounding rather than jurisdiction alone, while the broader reform process has remained reluctant to create new substantive obligations for investors.

From “Domestic Law” to “Legally Binding Instrument”: A Muted Transformation?

Environmental, labor, and social responsibilities are often enshrined at the national level and a number of delegations at the 53rd session, advocated using “domestic law” as the foundation for counterclaims (DP, para. 42), as these worries were connected to constitutional limitations (DP, para. 43) and particularly in regard to the jurisprudence of the Court of Justice of the European Union on the independence of EU law (see Komstroy case and Achmea case). An explicit allusion to domestic law ran the risk of putting arbitral tribunals in a situation where they might not be able to comply with those constitutional restrictions. The compromise used the more general phrase “legally binding instrument to which the respondent is a party” in place of the specific reference to domestic law (DP, para.44). It is incorrect to interpret this change as merely narrowing. It may broaden the scope of counterclaims to include duties resulting from human rights treaties, international environmental agreements, or other legally binding agreements that apply to the respondent State (WP.253, DP 19 on right to regulate). However, the action also shows that the reform's ambitions have been politically moderated (DP, paras. 42, 43 and 49).

To take into account constitutional concerns, the explicit domestic-law hook, which was symbolically potent for many developing States, was loosened. As a result, the formulation is more uncertain but also more flexible. Future interpretive practice will determine whether this uncertainty enhances or lessens DP 10's revolutionary potential. More generally, the change represents a move away from a strict domestic/international division and toward a multi-layered analysis of normative sources in which formal unity relates to the procedural basis of norms, while material unity is based on the substantive content and fundamental values like jus cogens. Then, it further demonstrates the constraints of incremental global reform by requiring structural recalibration to coexist with deeply ingrained constitutional restrictions.

Incremental Reform and Its Limits

The modular and stepwise approach to contemporary ISDS reform would be the proposed inclusion of DP 10 in an opt-in Protocol to the MIIR (DP, para. 53). Not all States may implement increased counterclaim proceedings immediately, but reform-minded States can promote procedural reciprocity without enforcing standard commitments according to the opt-in structure (DP, para. 58). The likelihood that a case will be automatically rejected for jurisdictional concerns may be reduced, which could increase procedural capacity for host States. The reform will give investors more predictability because the start of arbitration will have particular procedural ramifications. In addition to highlighting the need of adhering to relevant legal duties, this should aid in raising risk awareness. Additionally, DP 10 can have indirect behavioral consequences. Investors may more carefully integrate governance, environmental, and regulatory concerns at the outset if starting arbitration exposes them to related counterclaims.

When taken together, these factors imply that DP 10 is more than just a technical adjustment. It does not completely restructure substantive criteria, but it is a cautious move toward procedural parity and also supplements the UNCITRAL Arbitration Rules (DP, paras. 55, 59 and 60), as DP 10 addresses a critical flaw in its article 21(3). While this article of the Arbitration Rules formally allows counterclaims, it remains conditional on the tribunal having “jurisdiction over it”, a requirement that usually fails due to the lack of express investor consent in old-generation treaties. In current practice, as illustrated by the Kappes case, this condition turns article 21(3) into a “door without a key” due to the lack of express investor consent in the underlying treaty. DP 10 effectively breaks this jurisdictional deadlock, and by codifying implied consent, it provides the missing jurisdictional key, transforming a dormant procedural rule into an active mechanism for reciprocity, also as a cross-cutting reform, DP 10 effectively bridges the jurisdictional gap across various arbitration frameworks, providing the necessary consent to activate both article 21(3) of the UNCITRAL Rules and article 46 of the ICSID Convention. In this way, without turning ISDS into a general enforcement forum, implied consent connects procedural design with more general public-interest considerations.

However, the compromise reached in January 2026 indicates that deeper normative inequalities are still being carefully handled, even though procedural symmetry may be growing. The session in January 2026 demonstrated that while DP 10 opens the procedural door, the Draft Guidelines on Damages (WP.255) still reflect significant challenges in how State-led environmental or social harm is quantified, suggesting that procedural reciprocity is only the first step toward a truly balanced system. Indeed, the 53rd session highlighted a growing tension, while DP 10 lowers the jurisdictional threshold, the possible extension of security for costs to counterclaims could paradoxically deter States from using this new procedural right, effectively re-establishing an economic barrier where a legal one was removed.

Conclusion: Reciprocity and the Future of ISDS

By incorporating reciprocity into the act of initiation (DP, para. 45), DP 10 re-calibrates consent through jurisdictional estoppels, therefore an investor who triggers the arbitral process is precluded from later denying the tribunal’s competence over related counterclaims. However, DP 10 doesn't address more profound substantive issues in ISDS, like damages methodology or norms of protection, and substantive equality may not always follow from procedural reciprocity.Despite a recalibration demonstrated by the shift from the direct mention of domestic law to the more general idea of “legally binding instruments”, the January session highlights above all the boundaries of multilateral reform's willingness or ability to change the fundamental structure of ISDS.

While DP 10 offers a procedural fix within the existing system, the proposed permanent Multilateral Investment Court and its appellate body (WP.264, WP.259, WP.260, WP.256, WP.257) represent a more radical institutional shift toward a permanent, two-tier adjudicative body that could systematically integrate investor accountability. However, it is clear that DP 10 is not meant to establish a general regulatory complaint forum because of the insistence expressed by multiple delegations on a strict factual and legal link (DP, para. 52). Counterclaims will therefore continue to be directly related only to the investment claimant's defined issue (DP, paras. 46 and 47).

Recent UNCITRAL reforms further reinforce this trajectory, suggesting that reciprocity in ISDS is increasingly being constructed through cumulative procedural safeguards rather than a single doctrinal shift in consent, reflecting a gradual and multi-layered reconfiguration of ISDS that combines jurisdictional recalibration of consent (DP 10), procedural restructuring of arbitral proceedings (A/CN.9/1246) and institutional strengthening of State capacity within investment dispute settlement (A/CN.9/1265). It may become necessary in the future to procedurally integrate access to protection and the establishment of liability of investor rather than institutionally separate them if the ISDS mechanism is to maintain its normative credibility within the international legal order.