Paper M4 - Advising the Client and Writing a Legal Opinion
M4 asks for a legal opinion in response to a client enquiry: whether a competitor infringes, whether the client's own patent is valid, whether to oppose, or what a contract or procedural position means. The exam rewards structured reasoning, correct use of the applicable provisions, and a clear conclusion that names the remaining risk.
Structure of the opinion
- Facts as understood, with assumptions stated separately.
- Short answers to each question asked, placed before the analysis.
- Legal analysis, issue by issue, citing the provision and, where relevant, the case law.
- Risk assessment and options, with consequences of each.
- Recommendation and the decisions or instructions you need from the client.
Legal framework
- Infringement is a matter of national law; the EPC supplies Art. 64(1) EPC and Art. 69 EPC with its Protocol, which requires regard to equivalents while giving fair protection to third parties.
- After grant the claim may not be broadened (Art. 123(3) EPC); central limitation under Art. 105a EPC is a route, not a free choice.
- Entitlement rests with the inventor or successor (Art. 60(1) EPC); Art. 61 EPC gives the entitled person a route to the application.
- Transfers and licences require writing and signatures (Art. 72 EPC); registration (Art. 73 EPC) affects third parties.
- Forum matters: national courts, or the Unified Patent Court for European patents that have not been opted out.
Worked example
The client's granted claim requires features A, B and C. The competitor's product has A and B, with C replaced by an equivalent C' giving the same result. Reasoning: no literal infringement because C is absent; under Art. 69 EPC and the Protocol, ask whether the variant is obvious to the skilled person, solves the problem in substantially the same way, and whether fairness to third parties allows it. Conclusion: literal infringement unlikely, equivalence arguable but not certain, so a preliminary injunction is a risk-weighted decision, not a certainty.
Traps
- Stating a definitive infringement conclusion from the EPC alone, ignoring national law.
- Quoting Art. 69 EPC without the Protocol.
- Suggesting an amendment that broadens the claim after grant.
- Blurring validity and infringement, or omitting the assumptions on which the opinion depends.