After a 13 day trial, featuring 11 expert witnesses, the validity of Yeda’s glatiramer acetate patent has been upheld by Mr Justice Arnold in Generics (t/a Mylan) v Yeda and Teva [2012] EWHC 1848 (Pat). This case considered interesting issues relating to the clarity of drafting patent specifications and reliance upon post-published evidence in proceedings.


Yeda, the technology transfer company of the Weizmann Institute, has a patent for GA that is licensed exclusively to Teva (marketed by Teva as Copaxone). The patent relates to “Copolymer 1”, a polymer of a specified molecular weight range composed of four amino acids in particular ratios for the treatment of multiple sclerosis. Mylan challenged the validity of the patent in order to make way for its own generic GA treatment.


Arnold J’s lengthy decision addressed a multitude of issues including entitlement to priority, obviousness, insufficiency, added matter and non-infringement.

One of the most significant points of law considered by Arnold J related to the issue of whether the patent makes an inventive technical contribution to the prior art. Both sides accepted that if the patent, when read with the skilled person’s common general knowledge, did not disclose enough to make it plausible that the invention solved the technical problem, it was not permissible for the patentee to rely upon evidence that postdated the patent to demonstrate the technical effect. Mylan argued further that, even if the patent did make the invention plausible, it remained open to the other party to cast doubt on this through post-dated evidence.

Arnold J decided that post-dated evidence may be relied on to confirm that the disclosure in the patent either does or does not make it plausible that the invention solves the technical problem, but not to establish a technical effect that is not made plausible by the specification, or to contradict a technical effect that is made plausible by the specification. If the specification does make it plausible that the invention solves the technical problem, Arnold J determined that the party seeking revocation cannot rely upon post-dated evidence to cast doubt on whether the invention does solve the technical problem. Only evidence pre-dating the priority date may be relied on in this regard.

Significant consideration was also given to objections raised by Mylan concerning ambiguity. The patent defines Copolymer 1 as “a mixture of polypeptides composed of alanine, glutamic acid, lysine and tyrosine in a molar ratio of approximately 6:2:5:1” (author’s emphasis). Mylan submitted that the use of “approximately” is ambiguous, rendering the patent insufficient. Arnold J concluded that the skilled reader would have a willingness to understand and would look to the documents cited in the patent, rendering the definition difficult, but neither impossible to construe nor ambiguous.

Similarly, Mylan objected to the fact that while the patent made reference to molecular weight, it did not specify what method of measurement was used for the molecular weight. Arnold J admitted that at times he came close to concluding the patent was ambiguous in this respect, but determined that the skilled reader would work out the measurement technique applied as a result of being driven by a willingness to understand.

Ultimately Arnold J found the patent valid and infringed by Mylan’s product.


This decision should provide some comfort to patentees for two reasons. First, it prevents a patent, which disclosed what was thought to be a good invention at the time of application, from being revoked at a later date because subsequent advances in science reveal the invention did not actually solve the technical problem. Second, it suggests that the skilled reader’s willingness to understand is capable of overcoming fuzziness when the patent specification fails to address basic matters.