The Court of Appeal in Merck v Teva1 has upheld the first instance decision of Floyd J., that a patent for co-formulation of medicaments for the treatment of glaucoma was invalid for obviousness. The decision is particularly of note as the Court assessed, and rejected, an unusual argument raised by Merck, that where there was insufficient time for the skilled team to apply the teachings of the prior art, and so perform the trial and error necessary to reach the patented product before the priority date of the patent, the patent was not obvious.

Business Impact

  • The decision highlights the need to exercise caution when publishing material relating to an invention where the patent application for that invention is not yet filed.
  • The only date relevant when assessing obviousness is the priority date.
  • Parties must ensure that all arguments are raised at first instance; permission to rely on new points on appeal is not automatically granted.


The action relates to the treatment of glaucoma and, in particular, a patent claiming ophthalmic compositions containing timolol (the "gold standard" for treatment of glaucoma) and MK 507 (a product developed by the patentee, Merck).

The priority date for the patent was 17 April 1991. Some 6 days earlier, on 11 April 1991, a paper was published by authors including representatives of Merck, referring to the effect of consecutive administration of MK 507 and timolol. An application for invalidity was subsequently filed by Teva, in which that paper was cited as prior art.

Merck responded to the application for invalidity with two unsuccessful applications to amend the patent under s.75 Patents Act 1977. Floyd J. refused both applications and ordered that the patent be revoked. Permission to appeal was granted only in relation to the decisions on obviousness and added matter. In the event, it proved unnecessary to consider the added matter arguments.

Reasoning of the Court

The patentee relied upon two propositions in their appeal. First, an unusual argument based upon the short time that elapsed between publication of the prior art and the priority date; and, second, that the Judge wrongly applied hindsight when assessing obviousness.

The basis of the first proposition was that 6 days was insufficient for the skilled team to experiment with the teachings of the prior art, to see if the line of investigation was worth pursuing. Even if some preliminary investigations were concluded, they would merely show that some adjustments to the pH would be required. It was known that such adjustments might have a negative impact upon the activity of the co-formulation.

The Court of Appeal noted that neither s.2(2) of the Patent Act 1977, which defines the "state of the art", nor s.3 of the same Act, which prescribes the test for obviousness, contain any additional time requirement beyond that the relevant state of the art is that which exists at the priority date. Therefore, so long as by reference to the relevant state of the art the invention is obvious, it does not matter that it may take time to perform the necessary routine tests. Furthermore, the time taken to obtain regulatory approval is not relevant. This finding is consistent with the decision in Actavis v Merck2.

Finally, the Court noted that, as this argument was not raised at first instance, it was in any event not open to Merck to raise it on appeal.

In rejecting the patentee's second proposition, the Court upheld Floyd J.'s finding that the skilled team would be highly motivated to produce a co-formulated product. In reaching this conclusion it was relevant that co-formulation was well known in ocular treatment and could be a valuable and appropriate measure that would bring with it the advantage of patient compliance. The Court concluded that, although some trial and error was required, the need to adjust the pH of the formulation and to perform routine tests would not have led the skilled team to abandon the project.