New Book on Equality of Arms in EU Cross-Border Civil Litigation

In this post, Julie Esquenazi (University of Paris 1 Panthéon Sorbonne) presents the key findings of her doctoral thesis, recently published with Bruylant Larcier Intersentia on Equality of Arms in Cross-Border Civil Litigation. The research aims at analysing and determining whether and to what extent European rules of international jurisdiction effectively ensure equality of arms.

The Principle of Equality of Arms

The principle of equality of arms is enshrined in the principle of due process, guaranteed by Article 6, paragraph 1, of the European Convention on Human Rights. More specifically, it aims at ensuring a fair balance between the parties. According to the European Court of Human Rights (“ECHR” hereafter), that principle implies, in civil matters, that any party “must be afforded a reasonable opportunity to present his case – including his evidence – under conditions that do not place him at a substantial disadvantage vis-à-vis his opponent” (Case Dombo Beheer v. The Netherlands, Application no. 14448/88).

Insofar as it involves a comparison (stemming from the use of the comparative “vis-à-vis”), one would search the ECHR case law in vain for a threshold beyond which the equality of arms would be breached. Nevertheless, the analysis of the case law reveals one criterion: the breach in the equality of chances to sway the judge’s conviction, all other things being equal. Following the ECHR’s case law, two categories of imbalances may impair equality of arms between the parties. As stated in the Airey case, “a hindrance in fact can contravene the Convention just like a legal impediment”.

Context: European Jurisdictional Rules in Cross-Border Civil Litigation

The doctoral work aims at researching whether the application of jurisdictional rules place a party in a situation of substantial disadvantage vis-à-vis the other party, thus infringing the principle of equality of arms in a cross-border civil litigation context. Jurisdictional rules are generally confronted to the right of access to justice (established by the ECHR in the Golder case). But no study had been dedicated to jurisdictional rules from the perspective of the principle of equality of arms. Yet, in determining which party may plead at home and which one must bear the burden of internationality, the jurisdictional rule is likely to create a significant imbalance between the parties, potentially leading to a situation of one party being placed under a substantial disadvantage vis-à-vis his opponent. Because the determination of international jurisdiction is not neutral regarding the resolution of the dispute (e.g. application of the lex fori, application of the forum’s procedural rules, intervention of the forum’s mandatory provisions or public policy), the risk of violation of the equality of arms principle exists. Such risk should not, however, be overestimated. Most jurisdictional rules are reasonable and designate a forum which entertains a connection with the dispute, thus guaranteeing a priori that no party is under a substantial disadvantage vis-à-vis the other. Nonetheless, risks of infringement of the principle of equality of arms may be aggravated by the existence of a gross factual imbalance between the parties. The Wikingerhof case(analysed here and here) is particularly eloquent in this regard: the company running a hotel in Austria estimated that it did not freely consent to the unilateral modification of the terms of use of the platform booking.com because of the latter’s dominant position. The choice of court agreement in favour of The Netherlands’ courts, where Booking has its seat may actually place the Austrian company at disadvantage. The combination of gross imbalances and jurisdictional rules may infringe the principle of equality of arms.

Equality of Arms and Factual Gross Imbalances

The protection of “weak parties”

EU jurisdictional rules partially take into account factual gross imbalances. In civil and commercial matters, Brussels I bis Regulation provides for more favourable rules of jurisdiction to the interests of weaker parties (See Recital 18). As noted in the Shearson Lehmann case in the context of consumers, the ratio legis is “to ensure adequate protection for the consumer as the party deemed to be economically weaker and less experienced in legal matters than its counterparty”. The jurisdictional rule derogates from the more objective rules of jurisdiction, such as the forum rei, the forum contractus, or the forum delicti, in order to protect the weak party. In matters relating to insurance, or consumer contracts or individual contracts of employment, Sections 3, 4 and 5 of the Brussels I bis Regulation allow respectively an insured or beneficiary, a consumer, or an employee to seize a proximate judge. The general idea is not to compound the economic and informational imbalance with the burden of litigating in a distant and foreign jurisdiction.

In France, in the context of consumer contracts, recent case-law has gone even further when the Brussels I bis Regulation is not applicable. In two decisions of 25 March 2026, the French Cour de cassation (Cases no. 24-21.790 and 24-21.422) ruled that a choice of court agreement in favour of a non-EU State in a consumer contract could not deprive a consumer, who is domiciled in France at the time of the proceedings, of the right to seize French courts, while not requiring the condition of direction of activity (analysed here). Jurisdiction of French courts as the place of domicile of the consumer is a mandatory territorial jurisdiction rule, which may therefore set aside a choice of court agreement, as stated in the Sorelec case. This exception complies with the principle of equality of arms, which require the judges to act so that no party is in a situation of substantial disadvantage.

The lack of protection of small businesses

Yet, not all weaker parties are protected. As noted by Gisela Rühl, “the European legislator protects various categories of presumably weaker parties from the dangers of party autonomy. However, it is not apparent why certain parties – consumers, passengers, (mass) insurance policy-holders, employees, maintenance creditors – are protected, whereas others – such as tenants, franchisees or commercial agents – are not” (see here). Under EU law, weaker parties do not encompass professionals, no matter how small.

Gross imbalances between businesses are largely documented – in particular in light of the GAFAM and their relationships with professional users. The Small Business Act Communication shed light on the situation of small businesses in the EU. More recently, the Regulation Platform-to-Business aims at ensuring transparency and fairness in relations between digital platforms and their users, including professional users. In comparative law, a few countries have enacted pieces of legislation aiming at protecting small businesses. Under French civil law, a clause creating a significant imbalance may be neutralised, included when it is concluded by two professionals. Yet, that protection of small businesses does not extend in private international law. In particular, under the Brussels I bis Regulation, one would look in vain for any means to overcome a choice of court agreement that would eventually infringe the principle of equality of arms. While under The Hague Convention of 30 June 2005, a non-chosen judge may nonetheless admit its jurisdiction when it would lead to a “manifest injustice” or “contrary to the public policy” of the State of the seized court, it is not the case when the Brussels I bis Regulation applies. According to Article 25 of that text, the chosen court shall have jurisdiction unless the choice of court agreement is null and void as to its substantive validity under the law of the State of the designated court. Yet, in its Lastre decision (analysed here), the Court of Justice held that the concept of “null and void as to its substantive validity” should be autonomously construed: it refers to the general causes of nullity of a contract. It seems that the exception under French law of significant imbalance (déséquilibre significatif) under article 1171 of the French civil code does not fall under that definition because it applies to a contractual clause. It does not qualify as a general cause of nullity of a contract. The French Cour de cassation excluded that this exception be evaluated when the choice of court agreement designates another Member State as article 25 of the Brussels I bis Regulation applies (Case no. 23-12.384, mentioned here)

The risk of inequality of arms thus results from the lack of any means to overcome a choice of court agreement that would be particularly burdensome on one party.

The proposal

To overcome that difficulty, I have proposed the insertion of a new section, within the Brussels I bis Regulation. The new section would be devoted to establishing jurisdiction in relations between small and very big companies, when there is a structural imbalance between the parties. This section would apply, in contractual matters, in relations between a small enterprise and a big enterprise, both defined pursuant to different criteria in terms of number of employees as well as amounts of net annual turnover. Once these requirements are met, it establishes a rebuttable presumption that the section applies. The structure of the new section follows that of the individual employment contracts. It enables the small business to bring an action before the court of the State where, under the contract, the small enterprise executes the contract. With respect to choice of court agreements, they would be admissible to the same conditions: either because they are concluded after the dispute arises, or because they are concluded in order to enlarge the jurisdictional options of the small business.

The second part of the study envisages situations of potential breach of equality of arms absent any factual and structural imbalance between the parties.

Equality of Arms and Legal Imbalances

Imbalances due to the concurrent jurisdictions system

In the absence of factual imbalances between the parties, procedural imbalances may nonetheless result from applying an EU or national jurisdiction rule. But could infringement of the principle of equality of arms result from the European system of the Brussels I bis Regulation itself? Professor Mayer, in its course on coordination of state legal orders of The Hague Academy, has argued that the mere possibility for a plaintiff to be able to choose between different courts breaches that principle, because the respondent does not have that choice. On the one hand, the system of concurrent jurisdictions gives the plaintiff a choice in a large number of situations. On the other hand, the lis pendens system prohibits the respondent to seize another competent court once the first one has admitted its jurisdiction. The combination of the two may, in some circumstances, impair the principle of equality of arms. One topical example lies with negative declaratory judgments (see for instance, The Tatry case).

Rather than abolishing concurrent jurisdictions, I propose a hierarchical system inspired by family matters. For instance, in matter of matrimonial property regimes, Article 6 of the Regulation on Matrimonial Property Regimes foresees heads of jurisdiction “where no court of a Member State has jurisdiction pursuant to Article 4 or 5”. In the context of civil and commercial matters under Brussels I bis Regulation, for instance in contractual disputes, the forum contractus (Article 7(1)) would take precedence over the forum rei (Article 4), the latter remaining available only where the former falls outside the European judicial area. Because the forum contractus is based on a close connection between the forum and the action, which will likely involve both parties, it should therefore have priority over the general rule of the forum of the defendant’s domicile, whose connection is limited to one party. In that sense, equality of arms can be preserved while limiting the risks of denial of justice.

Imbalances due to a rule of jurisdiction

This issue is well documented with respect to exorbitant jurisdiction, such as article 14 of the French civil code. But it may also be the case of other rules. For instance, article 7, paragraph 2 of the Brussels I bis Regulation, as interpreted by the Court of Justice in the e-Date case, may give rise to judicial harassment, particularly in SLAPP litigation. A party aiming at introducing a SLAPP action would be able to seize all courts where the litigious content has been published worldwide. While the recent anti-SLAPP Directive introduces procedural safeguards and a head of jurisdiction when proceedings are brought outside the EU, it does not provide any mechanism allowing a Member State court to decline jurisdiction when its exercise places a party at a substantial disadvantage vis-à-vis its opponent.

To address this issue, I propose introducing a mechanism allowing a seized court to decline jurisdiction when its exercise violates the principle of equality of arms. In the European judicial area, the mechanism of transfer of jurisdiction appears relevant to mitigate the drawbacks of the forum non conveniens doctrine, specifically the risk of denial of justice for the plaintiff.