Skip to content


22 Apr 2020

The recent Court of Appeal judgment in Mexichem UK Ltd v Honeywell International Inc [2020] EWCA Civ 473 has upheld the first instance decision of Hacon J refusing to strike out Mexichem’s requests for Arrow declarations in relation to Honeywell’s patents and patent applications.

An Arrow declaration is a negative declaration made by the Court that a product or process was old or obvious at a particular date. As such, any patent claims with a priority date after that date cannot both cover the product or process in question and be valid. The aim of such declaratory relief is to protect against future infringement allegations related to granted or yet-to-be-granted, and potentially unknown, patents. Arrow declarations take their name from the case of Arrow v Merck [2007] EWHC 1900 (Pat), the first case in which such relief was sought, with subsequent cases seeking to define the boundaries of this form of relief. The recent Court of Appeal decision is the latest such case.

The present action relates to Honeywell’s patent portfolio of ten granted and pending patents for the use of two particular refrigerants (“ze” and “yf”) in mobile air-conditioning systems. Mexichem sought to revoke the six granted patents and obtain Arrow declarations with respect to the four pending divisional patents. In response, Honeywell sought to strike out the declarations.

At first instance Hacon J dismissed Honeywell’s contention that an Arrow declaration had to be sought in relation to a specific product or process. Declarations framed in more general terms, he held, could still have utility because “they are aimed at providing a finding of obviousness which can serve as an unchallenged foundation for argument on the inventive step of inventions claimed in patents which may be granted to the defendant in the future”.

Honeywell appealed, arguing that a declaration framed in such broad general terms lacked any real utility because no resolution could be achieved until after a second round of contested proceedings. Further, the judge had been wrong to treat the question of inventive step as something which can be sliced up into a series of steps and dealt with in turn. In relation to the latter, Honeywell argued that such a stepwise approach would have “distorted the exercise which the court was later required to perform”, which is to decide whether the invention as a whole is inventive.

In dealing with the clarity point, Floyd LJ referred to the Court of Appeal decision in Glaxo Group v Vectura [2018] EWCA Civ 1496. He stated that the wording of any declaration must inform the Court of the technical issues to be decided. As such, it must “identify the combination of features of the products and processes in question on which the assessment of obviousness is to take place”. However, it was reiterated that it is clear from Arrow v Merck and subsequent cases that there is no requirement for the declaration sought to identify all of the features of the product or process. As such, there is no threshold requirement that the party seeking an Arrow declaration must have an actual product in production or even a fully formulated product description.

While acknowledging that “the extent of generality or particularity of the declaration may affect the utility of the declaration”, Floyd LJ stated that this is “a matter of degree which it will be for the trial judge to assess.” Therefore, at this early stage of proceedings, it is sufficient for the party seeking an Arrow declaration to show that there is a real prospect of it being able to establish those matters at a trial. In relation to the broadness of the declaration sought, it was held that such a declaration might have utility because Honeywell had previously sought (in Germany) to protect the inventive concept of the patents couched in similarly broad terms.

In relation to Hacon J’s treatment of inventive step, Floyd LJ referred to the Supreme Court judgment in Actavis v ICOS [2019] UKSC 15. Whilst the step-by-step analysis of obviousness has been held to be unfair in many cases, there is a class of case in which it is relevant to consider each step in a putative series of steps to be taken by the skilled person and consider whether any of them individually, and in the end cumulatively, is obvious. Floyd therefore held that it is at least open to Mexichem to argue that a declaration about the step of deciding to use ze and yf for the claimed purpose would serve a useful purpose.

Though this decision may be perceived as a broadening of the scope and applicability of Arrow declarations, it remains to be seen whether Mexichem will actually succeed in obtaining the declarations sought when the facts and issues at hand are fully interrogated at trial.

The full judgment can be read here.

Headnote: Marcus Riby-Smith, Marks & Clerk