Cross-Border Enforcement Cooperation in Energy Markets

1. Introduction

Cross-border enforcement cooperation in energy markets means cooperation between regulators and other authorities of different countries to detect, investigate and enforce violations of energy-market rules.

This is especially important in electricity and gas markets because trading is not limited to one country. Electricity can be produced in one Member State, traded through an exchange in another, and delivered through an interconnector to a third country. A market participant can therefore affect prices or market conditions in several jurisdictions at the same time.

The EU's REMIT framework is a major example. REMIT prohibits insider trading and market manipulation in wholesale energy markets and establishes EU-wide monitoring of trading activity. ACER works with national regulatory authorities (NRAs) to identify and investigate possible breaches. (ACER)

2. Why Cross-Border Enforcement Is Necessary

National enforcement can be difficult when conduct has effects in several countries.

For example:

Company A → trades electricity in Country X → uses information from Country Y → affects prices in Country Z

A single national regulator may not have access to all relevant trading records and evidence.

Cross-border cooperation therefore helps authorities:

exchange market information;

identify suspicious transactions;

collect evidence;

coordinate investigations;

avoid duplicate investigations;

determine which authority should lead a case; and

apply energy-market rules consistently.

ACER states that it coordinates with national energy regulators as well as financial, competition and other relevant authorities. (ACER)

3. REMIT as the Main EU Framework

The Regulation on Wholesale Energy Market Integrity and Transparency (REMIT) is central to cross-border enforcement.

It prohibits:

Insider Trading

A market participant cannot use inside information to obtain an unfair trading advantage.

Market Manipulation

Market participants cannot engage in transactions or conduct designed to create false or misleading signals or artificially influence wholesale energy prices.

Failure to Disclose Information

Relevant inside information must be disclosed according to REMIT requirements.

Failure to Report Data

Market participants and relevant reporting entities have obligations to provide transaction information.

The revised REMIT framework, adopted in 2024, expanded ACER's role by giving it investigatory powers for certain cross-border cases involving two or more Member States. (ACER)

4. Role of ACER and National Regulators

The governance structure is important because ACER does not simply replace national regulators.

The basic structure is:

ACER
↓
Market monitoring and cross-border investigation
↓
National Regulatory Authorities
↓
National enforcement and sanctions

REMIT enforcement remains principally at national level. National regulators impose sanctions under the applicable national framework, while ACER has an important EU-wide monitoring and, for specified cross-border cases, investigatory role. (ACER)

ACER can collect and analyse market data and identify suspicious behaviour. Under the revised framework, it can conduct certain cross-border investigations, including requesting information, taking statements and carrying out on-site inspections. (ACER)

5. Cross-Border Investigation Procedure

A simplified process can be understood as follows:

1. Market monitoring
ACER and national regulators monitor wholesale energy transactions.

2. Suspicious activity identified
Unusual trading patterns or possible market manipulation may be detected.

3. Coordination
ACER consults the relevant NRAs.

4. Investigation
Depending on the circumstances, the relevant national regulator or ACER conducts the investigation.

5. Evidence collection
Authorities obtain trading records, communications, transaction data and other relevant evidence.

6. Investigation report
ACER may prepare a report where it conducts a cross-border investigation.

7. National enforcement
Relevant NRAs determine the appropriate enforcement measures under national law.

ACER's published procedure states that when an ACER investigation identifies a potential breach, it notifies the relevant NRAs, which must then report on the measures considered necessary. (ACER)

6. Important Case Laws

E-Control v ACER, Case T-63/16

This case concerned cross-border exchanges of electricity and the allocation of cross-border transmission capacity. The General Court examined the relationship between national regulatory authorities, ACER and the legal framework governing cross-border electricity capacity. (Infocuria)

Relevance: The case demonstrates that cross-border energy regulation requires clear institutional responsibilities and effective legal review of decisions affecting interconnected electricity markets.

Austrian Power Grid and Others v ACER, Cases T-606/20 and T-607/20

The General Court examined ACER's powers concerning methodologies for the European electricity balancing platform. The Court confirmed ACER's enhanced role in adopting decisions on certain cross-border energy matters. (Infocuria)

Relevance: This case demonstrates that EU-level regulatory cooperation can involve substantive decision-making where a matter has a significant cross-border dimension.

Germany v ACER, Case T-283/19

This case concerned the internal electricity market and cross-border electricity exchanges. The General Court dealt with procedural issues surrounding litigation involving ACER and national interests. (Eur-Lex)

Relevance: It illustrates the judicial dimension of cross-border energy governance and the importance of clearly defining the powers and procedures of EU energy institutions.

Aquind v ACER, Case C-46/21 P

Aquind concerned a proposed electricity interconnector between the United Kingdom and France and the regulatory exemption applicable to new interconnectors. The Court of Justice confirmed that ACER's Board of Appeal must undertake meaningful review of complex technical and economic assessments rather than limiting itself to checking only for manifest errors. (Eur-Lex)

Relevance: The case is important for cross-border infrastructure, regulatory supervision and effective judicial review.

7. Practical Example

Suppose a company operates electricity-generation assets in Germany and trades electricity in Germany, Austria and the Netherlands.

If the company deliberately withholds generation capacity in one market to influence prices in another, the conduct may have a cross-border market-manipulation dimension.

Authorities may therefore need to:

compare trading data across countries;

exchange evidence;

identify affected markets;

coordinate investigative responsibilities; and

determine appropriate national sanctions.

ACER has already used cross-border investigative coordination in practice. In one investigation initiated during the 2022 energy crisis, ACER worked with regulators from Austria, Germany and the Netherlands to gather evidence concerning potential REMIT breaches in wholesale gas markets. (ACER)

8. Current Legal Development

This area is developing rapidly. The revised REMIT framework entered into force in 2024, and ACER published detailed Rules of Procedure for cross-border investigations in February 2026. ACER states that its cross-border investigations are expected to begin in the second half of 2026. (ACER)

This represents an important development because the EU is moving from mainly national enforcement supported by EU coordination toward a system in which ACER has a more direct investigative role in specified cross-border cases, while national regulators retain responsibility for enforcement and sanctions. (ACER)

9. Conclusion

Cross-border enforcement cooperation in energy markets is based on shared monitoring, information exchange, coordinated investigations and cooperation between EU and national authorities.

The REMIT framework provides the clearest example. ACER provides an EU-wide perspective, while national regulators retain major enforcement responsibilities. Cases such as E-Control v ACER, Austrian Power Grid v ACER, Germany v ACER and Aquind v ACER demonstrate how courts have addressed the distribution of regulatory powers in interconnected electricity markets.

For PhD-level energy law, the central issue is the balance between effective cross-border enforcement and national regulatory authority, particularly as energy trading becomes more digital, interconnected and dependent on cross-border data.