How to respond if a competitor copies your software or interface

In brief

In France and the European Union, software source code is protected by copyright. Ideas and functionality generally remain free to use. A graphical user interface (UI) may be protected if original (as a work), but not under the specific protection for “computer programs”. Depending on what is copied, you will bring either infringement proceedings (code/original UI) or unfair competition/free-riding proceedings (slavish copying, confusion, appropriation of investment).

Useful legal framework: Directive 2009/24/EC (EUR-Lex), Court of Cassation judgment of 5 October 2022 on freedom to use functionality (Legifrance), criminal penalties for infringement (up to 3 years and €300,000: Intellectual Property Code, art. L.335-2), judicial court jurisdiction (Justice.fr).

What the law actually protects (and what it does not)

• Source (and object) code: automatically protected by copyright as a “computer program”. No mandatory deposit; you must nevertheless prove your rights (dating, ownership, originality). Basis: Directive 2009/24/EC (EUR-Lex).
• User interface: not covered by the specific protection for programs, but may be protected by copyright if original (choices and arrangement bearing the author's imprint). See the French case-law approach: Court of Cassation, 5 October 2022.
• Functionality, ideas, logic, programming languages, file formats: generally free to use. Copying functionality alone is not in itself infringement, unless unfair conduct is involved (confusion/appropriation). Confirmed by the Court of Cassation (Legifrance) and legal commentary (Deshoulieres Avocats).
• When should you pursue unfair competition/free-riding? If the other party creates confusion (very similar look & feel, identical screens and journeys) or “rides on your coattails” without creative effort. This route is often more effective than infringement when only appearance/usability is reproduced (Ref Avocats).

Worth knowing: lacking a protection strategy (evidence of prior creation, contracts, access control) increases economic risk in the event of leakage or copying (DGSI). To secure evidence of creation, use e-Soleau and INPI services (INPI).

Assessment: is your case infringement or unfair competition?

1. Does the copying concern code? Compare code sections, architecture, hashes and database structures where they reveal textual reproduction. Retain Git commits, CI/CD logs and earlier deposits.
2. Does the copying concern the interface? Record screens, sequences, micro-interactions and distinctive graphical choices. The more “slavish” the copying, the more relevant unfair competition/free-riding proceedings become.
3. Only functionality? Lawful in principle. You will need to demonstrate unfair conduct (privileged access to your beta, maintained confusion, disparagement, appropriation of investment) to act effectively (Ref Avocats).

A 72-hour action plan

1) Preserve the evidence (immediately)

• Judicial commissioner's report (formerly bailiff): capture screens, journeys, network resources and distributed versions.
• Timestamp your material: e-Soleau deposits (INPI), digital fingerprints, cold storage of repositories.
• Collect user journeys, graphics kits, Figma/Sketch exports, videos and product documentation.

Tip: the report must be reproducible, detailed and describe the technical context (browser, version, URL, timestamp).

2) Descriptive seizure/infringement seizure (within 3–10 days)

Under an order on an ex parte application from the president of the judicial court, a judicial commissioner and, if needed, an expert attend the competitor's or its hosting provider's premises to describe and/or seize material (code, binaries, servers, logs). Basis: copyright infringement seizure under the French Intellectual Property Code (Legifrance). Jurisdiction and procedure lie with the judicial court (Justice.fr).

3) Structured formal notice (within 48–72 hours)

Send a formal notice detailing: your rights (ownership, originality), the alleged acts (evidence), demands (cessation, removal, dismantling, compensation, disclosure of source materials), a short ultimatum and notice of measures (summary proceedings, seizure). Method and template: see our guide to effective formal notices.

4) Select and initiate the appropriate procedure

• Summary proceedings (urgency/clear-cut case) to obtain interim measures (cessation, confiscation, coercive fine) pending judgment on the merits (Justice.fr).
• Proceedings on the merits: infringement (where code or original UI is reproduced) and/or unfair competition/free-riding (where confusion/appropriation occurs). Both grounds may be combined.
• Criminal proceedings as a complement (deterrent effect): infringement is an offence (3 years, €300,000: art. L.335-2 CPI), but civil proceedings generally secure cessation faster.

Infringement versus unfair competition: how to decide

Infringement (code/original UI)

• Evidence of originality: creative contribution, free and arbitrary choices. Retain specifications, tickets and design rationale.
• Access and similarities: the more specific and numerous the similarities, the stronger the evidence. A descriptive seizure is often decisive.
• Exceptions: limited decompilation for interoperability (Directive 2009/24/EC: EUR-Lex).

Unfair competition/free-riding

• Confusion: similarities in interface, journeys or messages capable of misleading a normally attentive user.
• Free-riding: appropriation of your investment (slavish reproduction of your UI/UX, documentation, positioning), even without an immediate likelihood of confusion (Ref Avocats).
• Advantages: useful when only appearance is copied or code evidence is inaccessible.

For more on an unfair competition/free-riding strategy, see our dedicated guide: how to take action against unfair competition.

Common pitfalls (and how to address them)

• “Functionality is free to use”: true in principle. Your case must document the copied form (screens, wording, sequences), not the idea (Deshoulieres Avocats, Court of Cassation, 5 October 2022).
• Open source: if your code incorporates FLOSS components, check licences. The other party may lawfully reuse the same components… but not your proprietary code.
• Independent creation: anticipate the other party's defence by strengthening evidence of prior creation (e-Soleau, deposits, GPG-signed commits) (INPI).
• Weak licence clause: strengthen your licence agreements (audit, exit assistance, escrowed code access, penalties).

Prevention rather than cure: your priorities

• Protect code: rights-assignment procedures, repository security, segregated access, evidence of prior creation and copyright.
• Contractual framework: well-structured NDAs, software licences, terms of sale/use, anti-reverse-engineering clauses subject to statutory exceptions.
• IP strategy: software patents are tightly regulated in Europe; see what remains possible in certain technical cases (patents and software?).
• Internal governance: employee/partner exfiltration scenarios and remedies for source-code theft.

In practice, our Legal Ops teams can also help equip your processes (evidence register, formal notice templates, litigation playbooks).

Operational checklist

1. Commission a detailed official report (UI, flows, resources).
2. Consolidate evidence of prior creation (e-Soleau, commits, mock-ups).
3. Map what is copied: code versus interface versus functionality.
4. Prepare a descriptive seizure (draft summons, application).
5. Send a firm formal notice with quantified demands.
6. Choose the procedural route: summary proceedings + proceedings on the merits.
7. Assess communications risks (unfair competition).
8. Secure contracts and technical access.
9. Anticipate the other party's defences (free-to-use functionality, open source, independent creation).
10. Document your losses (losses, diversion, costs, disruption).