Mexichem UK Ltd v Honeywell International Inc

An Arrow declaration need not identify a fully formulated product or process. It may declare specified features of a proposed product old or obvious where the declaration is clear and would serve a useful purpose.

The required degree of particularity depends on utility and is for the trial judge. On an application to strike out or for summary judgment, the claimant need only show a real prospect of establishing clarity and utility at trial. A declaration about one step in developing a product may be useful, especially where the anticipated research path is foreseeable or the patentee seeks protection for an equally broad inventive concept.

The claimant sought revocation of six patents relating to refrigerants used in mobile air-conditioning systems. It also sought Arrow declarations that, at the patents’ priority dates, it was obvious in the light of specified prior art to use either of two known refrigerants for that purpose. The declarations were intended to protect against patents which might later be granted on pending divisional applications.

Honeywell applied to strike out the declaratory claims or for summary judgment, arguing principally that they did not identify a specific product or process and lacked clarity and utility. HHJ Hacon refused the application in [2019] EWHC 3377 (Pat). The appeal concerned whether declarations framed at that level of generality had a real prospect of being granted at trial.

1. Appeal dismissed. The judge was entitled to refuse both strike-out and summary judgment. Mexichem had a real prospect of establishing at trial that the declarations were clear and useful. Lewison LJ agreed with Floyd LJ.

2. The court has a broad and flexible discretion to grant declaratory relief where it serves a useful purpose. The underlying issue must be defined clearly enough to be justiciable. An Arrow declaration must identify the features or combination of features upon which obviousness is to be assessed, but it need not describe every feature of a product or process. There is no threshold requirement for a fully formulated product description or a product already in production. The appropriate degree of generality is a matter for the trial judge.

3. The proposed declarations were not to be construed like patent claims. They sought to establish only that the idea of using the two disclosed refrigerants in a mobile air-conditioning system was obvious. Their silence about lubricants, additional refrigerants and other features did not declare combinations involving those matters obvious.

4. A broad declaration concerning an isolated step may sometimes lack utility, particularly where the judgment in the revocation proceedings already resolves the point. The warnings against hindsight-based, step-by-step analysis of obviousness remain important. However, a step-by-step analysis may be legitimate where the research programme which the notional skilled person would undertake is clearly foreseeable and the steps can be identified without hindsight. The evidence at trial might show that selecting the refrigerants was such a step.

5. The declarations might also address an inventive concept framed as broadly as concepts which Honeywell was seeking to protect. They could preserve Mexichem’s procedural ability to obtain adjudication even if Honeywell surrendered, revoked or amended the existing patents, and could assist against later patents arising from divisional applications. These possible uses were sufficient at the interim stage; their ultimate utility remained for determination at trial.

1. Court of Appeal (Civil Division): In [2020] EWCA Civ 473, the court dismissed Honeywell’s appeal and upheld the refusal to strike out the claim for Arrow declarations or grant summary judgment.
2. High Court, Intellectual Property List: In [2019] EWHC 3377 (Pat), HHJ Hacon held that the proposed declarations were clear and might serve a useful purpose despite not describing a fully specified product or process.