Competition Law and Security Platform Interoperability

1. Introduction

Security platform interoperability refers to the ability of cybersecurity and security-related platforms to communicate, exchange data, authenticate users, share threat intelligence, integrate APIs, and operate with products supplied by competing firms.

Examples include:

• endpoint-security software interoperating with operating systems;
• identity and access-management systems interoperating with cloud platforms;
• cybersecurity products accessing APIs of dominant platforms;
• security-information and event-management (SIEM) systems receiving data from competing products;
• threat-intelligence sharing between security providers;
• authentication and identity protocols;
• security software integrating with enterprise operating systems;
• cloud-security tools interoperating with dominant cloud infrastructure;
• vulnerability-management platforms accessing security telemetry.

Interoperability can increase competition because customers can combine products from different suppliers instead of being locked into one ecosystem. At the same time, a platform operator may legitimately restrict interoperability where unrestricted access creates genuine risks to security, authentication, privacy, system integrity or resilience.

Competition law therefore asks an important question:

Is a security restriction genuinely necessary to protect the platform, or is security being used as a justification for excluding competing products?

The issue is particularly important under Article 102 TFEU, national abuse-of-dominance provisions, and U.S. antitrust law concerning monopolization and essential facilities/interoperability.

The European Commission and the U.S. FTC have both recognized that interoperability and security can coexist, while emphasizing that security justifications should be examined carefully rather than automatically accepted.

2. Meaning of Security Platform Interoperability

Interoperability may occur at several levels.

A. Technical interoperability

Two security products can technically communicate with each other.

Examples:

• API access;
• common authentication protocols;
• standardized security telemetry;
• SIEM integration;
• endpoint-security interfaces.

B. Functional interoperability

A third-party security product can perform substantially the same security-related function within a dominant platform.

For example, an independent security application may need access to operating-system interfaces in order to provide:

• malware detection;
• device monitoring;
• identity verification;
• threat detection.

C. Data interoperability

Security platforms may need access to:

• logs;
• authentication data;
• threat indicators;
• vulnerability information;
• security events;
• telemetry.

A dominant platform can potentially disadvantage rivals by withholding such data or providing inferior access.

D. Cross-platform interoperability

A security product may need to work across:

• Windows;
• macOS;
• Android;
• cloud platforms;
• enterprise networks;
• identity providers.

E. Security-sensitive interoperability

This is the most difficult category.

Interoperability may itself create risks involving:

• malware;
• unauthorized access;
• credential theft;
• data leakage;
• privilege escalation;
• circumvention of security controls;
• attacks on critical infrastructure.

Consequently, competition law does not necessarily require unrestricted interoperability.

3. Competition Concerns

A. Refusal to provide interoperability information

A dominant platform may possess technical information necessary for competing security products.

If it refuses to disclose that information, competitors may be unable to develop effective products.

The classic example is Microsoft's refusal to provide interoperability information concerning Windows work-group server operating systems. The EU courts upheld the finding that the refusal could constitute abuse where the information was indispensable and the conduct threatened competition.

The same reasoning can become relevant to:

dominant operating system + security API + competing cybersecurity product.

B. API discrimination

A dominant security platform may provide its own security products with:

• richer APIs;
• faster API access;
• greater telemetry;
• privileged permissions;
• deeper system integration,

while competitors receive restricted access.

This can produce a competitive advantage even where formal access exists.

Thus:

Formal interoperability ≠ effective interoperability.

Competition authorities may examine whether the access supplied to competitors is genuinely sufficient to compete.

C. Self-preferencing through interoperability

A platform operator may make its own security product interoperable with its platform while making competing products technically inferior.

For example:

Platform

→ full security telemetry → platform's security product

→ limited telemetry → independent security provider

The result may be foreclosure of competing security providers.

D. Security-based exclusion

A dominant undertaking may argue:

"We cannot permit interoperability because it would compromise security."

This may be a legitimate justification.

However, the relevant competition-law question is generally whether:

1. the security risk is genuine;
2. the risk is technically demonstrated;
3. interoperability actually causes the risk;
4. less restrictive safeguards are available;
5. the restriction is proportionate;
6. the dominant firm applies the rule consistently.

The 2025 Alphabet interoperability judgment is especially important because the Court expressly addressed platform integrity and security as potential objective justifications for refusing interoperability.

4. Essential-Facility and Refusal-to-Deal Principles

Interoperability disputes frequently resemble refusal-to-deal cases.

The traditional European test comes from cases such as Bronner.

The question may involve:

• indispensability;
• elimination of effective competition;
• inability to reproduce the facility;
• consumer harm;
• objective justification.

However, digital platforms require more nuanced analysis because interoperability may make a product more attractive without being absolutely indispensable.

The 2025 Alphabet judgment is particularly significant because the Court held that lack of strict indispensability does not automatically prevent a refusal to ensure interoperability from being abusive where the interoperability can make the third-party app more attractive and the other Article 102 requirements are satisfied.

5. At Least Six Important Case Laws

1. United States v. Microsoft Corp. — U.S. District Court / D.C. Circuit

Key issue: interoperability between Windows and competing middleware.

Microsoft's control over Windows allowed it to influence how competing middleware products interacted with the operating system.

The litigation established important principles concerning:

• platform power;
• technological integration;
• exclusionary conduct;
• access to platform interfaces;
• interoperability;
• protection of competition in adjacent software markets.

The eventual remedies included requirements concerning interoperability and access to information necessary for competing products to interoperate with Windows.

Relevance to security platforms

A modern cybersecurity platform may similarly depend upon interfaces controlled by a dominant operating-system provider.

The case demonstrates that control over a technological platform can become an antitrust concern when the platform operator uses that control to disadvantage competing products.

2. Microsoft Corp. v. Commission — Case T-201/04

Court: Court of First Instance/General Court of the European Union
Subject: refusal to supply interoperability information.

This is one of the most directly relevant cases.

Microsoft was found to have abused its dominant position by refusing to provide competitors with interoperability information necessary for competing work-group server operating systems.

The Court examined whether:

• interoperability information was indispensable;
• competitors could realistically remain in the market without it;
• the refusal eliminated effective competition;
• there was objective justification.

The Court recognized that interoperability is a matter of degree, rather than a simple yes/no concept.

Security-platform application

Suppose a dominant cloud platform gives its own security product access to complete authentication and telemetry information but gives competing cybersecurity firms insufficient information to build interoperable products.

Microsoft v Commission provides a major analytical framework for assessing such conduct.

3. Alphabet Inc. and Others v AGCM — Case C-233/23

Court: Court of Justice of the European Union, Grand Chamber
Judgment: 25 February 2025

This is particularly important for modern digital-platform interoperability.

The case concerned refusal by a dominant platform to ensure interoperability between its platform and a third-party application.

The Court held that refusal to ensure interoperability can constitute abuse even where the platform is not strictly indispensable for the downstream product, where interoperability could make that product more attractive and other requirements for abuse are satisfied.

Most importantly for security-platform disputes, the Court addressed platform integrity and security.

A dominant undertaking may rely on security as an objective justification where providing interoperability would itself compromise platform integrity or security, or where interoperability cannot technically be achieved. But where those circumstances are absent, the undertaking may have to develop an appropriate interoperability mechanism within a reasonable period, potentially for appropriate remuneration.

Importance

This case provides an exceptionally useful framework:

Interoperability request

↓

Potential competitive effect

↓

Objective justification

↓

Security/integrity assessment

↓

Necessity and proportionality

↓

Possible interoperability remedy

4. Bronner v Mediaprint — Case C-7/97

Court: Court of Justice of the European Union

The case concerned refusal of access to a newspaper distribution system.

The Court established the stringent conditions traditionally associated with compulsory access to infrastructure controlled by a dominant undertaking.

Important considerations include:

• indispensability;
• elimination of competition;
• absence of realistic alternatives;
• whether access is necessary for competition.

Relevance

A security platform may argue:

"Our API is simply an optional feature, and competitors can develop alternative security mechanisms."

The Bronner principles make the availability of alternatives highly relevant.

But Bronner must now be read alongside more recent digital-platform jurisprudence, particularly Alphabet, where the Court recognized that interoperability may have competitive significance even when the platform is not strictly indispensable.

5. IMS Health GmbH & Co. OHG v NDC Health — Joined Cases C-418/01

Court: Court of Justice of the European Union

IMS Health concerned access to a copyrighted brick-structure used for pharmaceutical sales data.

The Court considered when refusal to license/access intellectual property could amount to abuse.

The case is relevant to interoperability because technical standards, interfaces and proprietary systems may be protected by intellectual-property rights.

Competition-law significance

A dominant security-platform operator cannot necessarily argue:

"The interoperability information is proprietary, therefore competition law can never require access."

Instead, the circumstances surrounding the refusal must be examined.

Security application

A cybersecurity company may need access to:

• proprietary APIs;
• authentication protocols;
• technical specifications;
• interoperability documentation.

The competition-law analysis must balance:

IP rights + innovation incentives + security + competition.

6. Slovak Telekom a.s. v Commission — Joined Cases C-165/19 P and C-166/19 P

Court: Court of Justice of the European Union

The case concerned access to telecommunications infrastructure and exclusionary conduct by a dominant undertaking.

It is important because it demonstrates how competition law approaches access to infrastructure and exclusionary strategies in network industries.

Relevance to security platforms

Cybersecurity platforms increasingly function as network infrastructure.

Examples include:

• identity infrastructure;
• cloud security;
• authentication systems;
• threat-intelligence networks;
• security monitoring infrastructure.

Where a dominant undertaking controls an important infrastructure layer and restricts access to competing providers, the principles concerning access and foreclosure become relevant.

7. MCI Communications Corp. v AT&T

Court: U.S. Court of Appeals for the Seventh Circuit

This is a foundational U.S. case concerning the essential facilities doctrine.

The dispute involved access to AT&T's telecommunications network.

The case is historically important because it articulated factors concerning:

• control of a facility by a monopolist;
• inability of competitors reasonably to duplicate it;
• denial of access;
• feasibility of providing access.

Relevance to security interoperability

A modern security platform may resemble infrastructure when it controls:

• authentication;
• identity;
• security telemetry;
• access-management systems;
• enterprise security APIs.

If competing providers cannot reasonably reproduce the required interface, refusal of access may raise stronger competition concerns.

6. Comparative Legal Principles From the Cases

7. Security Justification: When Can It Be Legitimate?

Security is different from a purely commercial justification.

A platform operator may have legitimate reasons to restrict interoperability where access could:

1. Create authentication vulnerabilities

Third-party access could enable:

• credential compromise;
• privilege escalation;
• impersonation.

2. Expose sensitive data

Interoperability may give access to:

• personal data;
• enterprise data;
• security logs;
• confidential information.

3. Increase attack surfaces

Every additional integration can potentially create:

additional interface → additional vulnerability → additional attack surface.

4. Undermine platform integrity

A security platform may need to prevent third parties from modifying:

• kernel-level components;
• authentication mechanisms;
• security policies;
• trusted execution environments.

5. Facilitate malware

Uncontrolled interoperability may allow malicious software to exploit legitimate security APIs.

8. When Security May Become an Antitrust Concern

A security argument becomes more problematic where:

• the security risk is unsupported by technical evidence;
• the restriction applies only to competitors;
• the dominant firm's own products receive broader access;
• less restrictive safeguards are available;
• competitors are given unnecessarily limited APIs;
• the platform changes technical specifications specifically to disadvantage rivals;
• security standards are applied inconsistently;
• access is technically possible but deliberately delayed;
• interoperability is withheld while the platform simultaneously expands into the same downstream market.

Thus:

Security is a legitimate competition consideration, but "security" is not automatically a competition-law exemption.

The FTC has expressly stated that privacy and security claims used to restrict interoperability should be scrutinized case-by-case and should not be accepted where they operate merely as a pretext for anticompetitive conduct.

9. Proportionality Analysis

A useful competition-law framework is:

Step 1 — Identify dominance

Is the platform operator dominant in:

• operating systems;
• cloud infrastructure;
• identity management;
• cybersecurity;
• endpoint security;
• enterprise security?

Step 2 — Identify the interoperability dependency

What does the rival need?

• API;
• authentication;
• data;
• telemetry;
• technical documentation;
• software interface;
• security protocol?

Step 3 — Establish competitive effects

Does the refusal:

• prevent market entry?
• raise rivals' costs?
• reduce product quality?
• prevent switching?
• reinforce ecosystem lock-in?
• protect the dominant firm's downstream product?

Step 4 — Examine security justification

What specific security risk exists?

Step 5 — Examine alternatives

Could the risk be addressed through:

• certification;
• sandboxing;
• encryption;
• rate limits;
• authentication;
• access controls;
• auditing;
• monitoring;
• contractual safeguards?

Step 6 — Apply proportionality

The question becomes:

Could substantially equivalent security be achieved through a less restrictive interoperability mechanism?

If yes, an absolute refusal becomes more difficult to justify.

10. Interoperability and Network Effects

Security platforms frequently exhibit strong network effects.

For example:

More users

↓

More security data

↓

Better threat detection

↓

More attractive security platform

↓

More users

This can produce a reinforcing cycle.

If a dominant platform also prevents competing security products from interoperating with its ecosystem, the network effect may become a mechanism for market foreclosure.

11. Interoperability and Switching Costs

Interoperability can reduce switching costs.

Without interoperability:

Customer → Platform A → proprietary security system

Switching to Platform B may require:

• replacing security tools;
• retraining employees;
• migrating logs;
• rebuilding authentication;
• changing APIs;
• changing compliance systems.

With interoperability:

Customer → Platform A + Security Provider B

the customer can use multiple suppliers.

Therefore, interoperability can facilitate multi-homing and supplier switching.

12. Data Portability and Security Interoperability

Interoperability is increasingly connected with data portability.

A customer may need to move:

• security logs;
• identity information;
• threat intelligence;
• incident records;
• configuration data;
• vulnerability histories.

Restrictions on data portability can therefore reinforce platform lock-in.

However, security and privacy protections may require:

• encryption;
• authentication;
• access controls;
• consent mechanisms;
• secure transfer protocols.

Competition law should therefore distinguish between:

legitimate secure portability mechanisms

and

unnecessary restrictions that prevent competitive switching.

13. Non-Discrimination

A particularly important remedy is non-discriminatory interoperability.

A dominant platform could be required to ensure that:

competing security providers receive technically equivalent access to relevant interfaces, subject to legitimate security requirements.

For example:

The objective is not necessarily identical treatment in every technical detail, but competitive neutrality consistent with legitimate security requirements.

14. Possible Competition-Law Remedies

Authorities may consider:

A. API access

Require access to necessary APIs.

B. Technical documentation

Require disclosure of interoperability specifications.

C. Non-discrimination

Prevent preferential treatment of the platform's own security product.

D. Data portability

Permit secure transfer of relevant security data.

E. Interoperability standards

Require adherence to neutral technical standards.

F. Independent monitoring

A monitoring trustee or technical auditor may assess compliance.

G. Security certification

Third parties can obtain access subject to objective security requirements.

H. Firewalls and sandboxing

Interoperability can be allowed while reducing security risks.

15. Special Importance of the 2025 Alphabet Judgment

For a modern examination answer, Alphabet v AGCM, C-233/23 deserves particular attention.

It develops the traditional refusal-to-deal doctrine for digital ecosystems.

The Court recognized that:

1. interoperability may be competitively important even without strict indispensability;
2. refusal can potentially hinder competition;
3. continued growth of competitors does not automatically disprove anticompetitive effects;
4. the dominant undertaking may invoke legitimate objective justifications;
5. security and platform integrity can constitute such justification;
6. the security justification must be connected to the actual technical circumstances;
7. where interoperability is technically feasible and security objections do not justify refusal, an appropriate interoperability solution may be required. 

This is highly applicable to cybersecurity, cloud-security, identity and security-platform disputes.

16. Relationship Between Competition and Cybersecurity Regulation

Competition law should not operate in isolation.

Security platforms may simultaneously be subject to:

• data-protection law;
• cybersecurity regulation;
• sector-specific regulation;
• critical-infrastructure requirements;
• consumer protection;
• intellectual-property law;
• contractual security obligations.

A competition authority therefore has to avoid creating an interoperability remedy that itself requires the dominant firm to violate mandatory cybersecurity or privacy obligations.

The appropriate solution may instead be:

controlled interoperability

rather than:

unrestricted interoperability.

17. Hypothetical Example

Assume SecureCloud operates a dominant enterprise cloud platform.

It provides its own endpoint-security product with:

• complete API access;
• real-time telemetry;
• privileged authentication;
• security-event feeds.

A competing cybersecurity company, CyberGuard, requests equivalent access.

SecureCloud refuses, stating:

"Opening the API would create cybersecurity vulnerabilities."

CyberGuard argues that SecureCloud's own security product receives access that is denied to competitors.

Competition-law analysis

1. Dominance

Determine whether SecureCloud possesses substantial market power.

2. Relevant interface

Determine whether the API and telemetry are commercially significant.

3. Competitive effect

Determine whether the refusal materially disadvantages CyberGuard.

4. Security evidence

SecureCloud should identify the specific vulnerability.

5. Less restrictive alternatives

Could access be provided through:

• certification;
• authentication;
• sandboxing;
• encryption;
• monitoring?

6. Discrimination

Why does SecureCloud's own product receive broader access?

7. Proportionality

Is complete exclusion necessary, or would controlled interoperability sufficiently protect security?

This approach closely reflects the principles emerging from Microsoft, Bronner, IMS Health, Slovak Telekom, MCI v AT&T, and especially Alphabet.

18. Key Legal Principles From the Six+ Cases

Microsoft v Commission

Interoperability information can be a critical competitive input.

United States v Microsoft

Control over a technological platform can generate antitrust liability where platform power is used to restrict competing technologies.

Bronner

Compulsory access requires careful consideration of indispensability and alternatives.

IMS Health

Proprietary rights do not automatically defeat competition-law intervention in exceptional circumstances.

Slovak Telekom

Access restrictions in network infrastructure can constitute exclusionary conduct.

MCI v AT&T

Control over infrastructure and denial of access can be relevant to monopolization analysis.

Alphabet v AGCM

Digital-platform interoperability receives a more nuanced Article 102 analysis, with security and platform integrity recognized as possible objective justifications.

19. Conclusion

Security platform interoperability sits at the intersection of competition, technology, cybersecurity and platform regulation.

The central competition-law tension is:

Interoperability promotes competition, switching and innovation; security restrictions may be necessary to protect the integrity of the platform.

Competition law therefore should not impose interoperability mechanically. The critical questions are whether the platform is dominant, whether access is competitively significant, whether the refusal produces exclusionary effects, whether the security concern is genuine and technically substantiated, and whether less restrictive means of achieving the same security objective are available.

The jurisprudence has evolved from traditional essential-facility and refusal-to-deal cases such as Bronner and MCI v AT&T, through the major interoperability ruling in Microsoft, toward the more flexible digital-platform approach reflected in Alphabet v AGCM (2025).

For security platforms, the emerging principle can therefore be expressed as:

Dominance + competitively significant interoperability + exclusionary effect
→ scrutiny of refusal/restriction
→ genuine security justification examined
→ necessity + proportionality + alternatives
→ possible controlled interoperability remedy.