Designing remedies is rarely straightforward. It requires balancing legal, economic and practical considerations, to ensure interventions are both effective and proportionate and that they meet the criteria described above. This task becomes even more demanding in the current enforcement landscape, where markets are increasingly global, complex and dynamic. In such an environment, a unilateral approach to remedy design might prove insufficient. Authorities face information asymmetries (vis-à-vis investigated or merging parties, but also sectoral regulators and other public and private actors), and a growing probability that remedies adopted in one jurisdiction will interact with or even contradict those imposed elsewhere. These challenges explain why co-operative approaches to remedy design have gained prominence and why they are increasingly important.
Recent ex post assessments of remedies suggest that effectiveness cannot be taken for granted and this provides useful context for understanding the growing focus on co-operation in their design. The European Commission’s study on twenty years of antitrust remedies1 found that although most commitments were formally implemented, fewer than half achieved their intended competitive effect (European Commission: Directorate-General for Competition et al., 2025[15]). Behavioural measures in particular were cited as toothless, partly because of the absence of adequate monitoring mechanisms and the lengthy duration of proceedings, which undermined their impact. By contrast, a comprehensive, although less recent review conducted by the US Federal Trade Commission of nearly 90 merger remedy orders adopted between 2006 and 2012 reached more optimistic conclusions: around 80% of remedies maintained or restored competition, with divestitures of ongoing businesses proving especially reliable (US Federal Trade Commission, 2017[16]).
These studies highlight that the way in which remedies are designed (including the degree of engagement with parties, potential buyers and market participants) can play a decisive role in their success. In this context, co-operation can improve the quality, feasibility and legitimacy of remedies. It helps address information asymmetries and reduces the risk of conflicting or inconsistent measures. A co‑operative process can also facilitate faster, smoother implementation and greater compliance, as parties are more likely to support remedies they helped shape.
This section sets out the main reasons for adopting a co-operative approach in remedy design. It highlights the benefits for competition authorities in terms of remedy effectiveness, proportionality and enforceability.
Co-operation in remedy design matters for several reasons. First, it responds directly to the complexity of modern markets, in which competition authorities cannot always rely solely on their internal expertise to identify and implement suitable solutions. Remedies (both behavioural and structural) often involve highly technical issues. The design of remedies is not a purely legal exercise, it depends on an accurate understanding of business models, technological dynamics and consumer behaviour, which often requires input by other stakeholders. Co-operation enables competition authorities to bridge knowledge gaps and to test whether proposed measures will function effectively in practice.
Second, co-operation mitigates the risk of fragmented or conflicting outcomes. In a context where mergers are often notified in multiple jurisdictions or where conduct by large multinational firms can have effects across borders, the likelihood of parallel enforcement is high. If each authority designs remedies independently, the outcome may be fragmented and inconsistent (OECD, 2024[6]). Remedies imposed in one jurisdiction may render those in another less effective, or they may generate contradictory incentives that increase costs for firms and consumers alike. Co-operation helps ensure that the remedial package contributes to preserving competition, rather than creating new distortions. For the firms concerned, consistency also facilitates compliance, as co-operation can contribute to avoiding inconsistent remedies (EU Merger Working Group, 2011[17]). For the authorities, co‑ordination reduces duplication of efforts and supports international comity. In this regard, the OECD Recommendation Concerning International Co‑operation on Competition Investigations and Proceedings [OECD/LEGAL/0408] calls on its adherents to co-ordinate the design and implementation of remedies and avoid possible conflicting approaches and outcomes.
There are specific contexts in which the case for co-operation is particularly strong. Cross-border merger cases are one of these. Each authority must ensure that its own competition concerns are addressed, yet the remedies imposed should, when possible, aim at allowing for the consummation of mergers that may generate efficiencies and welfare gains globally (OECD, 2024[6]). Similarly, when conduct has effects in multiple jurisdictions, alignment in remedies may boost their efficiency. In these settings, the goal is not necessarily to reach identical outcomes everywhere, but to avoid inconsistent ones (OECD, 2024[6]). Divergences in remedy packages are acceptable so long as they do not contradict one another. One risk that is worth considering in the design of remedies is when uncoordinated remedies push the parties to abandon a transaction that could have been rendered benefits without harming competition through a consistent package across jurisdictions (OECD, 2024[6]) or that generate suboptimal outcomes for jurisdictions aiming at correcting anticompetitive behaviour. Co-operative approaches to remedy design (through various mechanisms, described in Section 4 below) can therefore prevent contradictory outcomes and maximise both the effectiveness and implementation of interventions.
Third, co-operative approaches enhance the acceptance of remedies. Parties may be more likely to comply with conditions they have had the opportunity to shape. For instance, in merger review, merging parties may provide detailed information on the conditions for the implementation of the remedies (ICN, 2016[18]). Simultaneously, remedies that reflect input from different regulators, consumers and market participants are more likely to proportionally and effectively address competition concerns. They also allow authorities to benefit from early warnings about unintended consequences or implementation difficulties, having the potential to improve the overall quality of the outcome.
Sectors subject to specific regulation also illustrate the importance of co-operative design. In industries such as telecommunications, energy, transport or financial services, competition remedies frequently overlap with the mandates of sectoral regulators and other relevant public bodies. In these settings, the existence of regulation does not necessarily remove the need for an antitrust remedy, but it does shape how such remedies can be designed and implemented (Antitrust Division, U.S. Deparment of Justice, 2020[19]). Co-operation with the relevant regulatory agency is therefore beneficial: it allows authorities to avoid imposing remedies with inconsistent requirements and ensures that remedies do not contradict regulatory frameworks. In some instances, regulators may even be better placed than competition authorities to monitor compliance, given their ongoing supervision of the sector (see section 4.1). Engaging with them during the design phase can help to secure remedies that are not only effective and proportionate but also feasible within the broader regulatory framework.
The digital economy further strengthens the rationale for co-operation. Digital markets are characterised by multi-sided platforms, strong network effects and rapid innovation cycles. Remedies in these contexts are especially difficult to design because they often target conduct embedded in product design, algorithms or business models. Box 2 describes some characteristics unique to digital markets that make co-operation particularly relevant in remedy design in these markets.