In an unusual turn of events, evidence given by an expert witness in the Federal Court of Australia has been turned on its head by that same witness’ own admissions sworn over 10 years ago in an Affidavit in respect of an unrelated trial.

In Bayer Pharma Aktiengesellschaft v. Generic Health Pty Ltd (No 2) [2013] FCA 279, one of the expert witnesses gave evidence for the Respondent, Generic Health, that was inconsistent with sworn information in an Affidavit that was filed during a previous unrelated trial. The earlier trial reported as Aktiebolaget Hässle v. Alphapharm Pty Ltd [1999] FCA 628, concerned a Patent having a priority date of 30 April 1986 for the drug omeprazole. In the present case, the priority date of the Patent was 31 August 1999. Despite the 13 year time difference, it was considered that the state of the art was consistent during this period, the result being that the expert witness’ own words were used to discredit and undermine his evidence concerning what the skilled person would have done at the relevant priority date in Australia.

Briefly, the Applicants in the present case have the benefit of the patent-in-suit, which relates to a pharmaceutical composition comprising drospirenone (“DRSP”) and ethinylestradiol (“EE”). This composition is supplied as oral contraceptive products under the brand names Yasmin and Yaz in Australia. The Applicants contended that the Respondents’ oral contraceptive product sold under the brand name Isabelle in Australia infringed the patent-in-suit.

One of the issues to be resolved was whether an “enteric coating” applied to the composition involved an inventive step. An enteric coating protects the active pharmaceutical ingredient (“API”) during transit through the stomach and delays the release of said ingredient, until it enters the small intestine. In relation to this particular issue, the witness gave evidence that an enteric coating was reasonably common in Australia in the 1970s and that by 1999, its use was very common. Difficulties concerning the use of enteric coated compositions were highlighted during the trial. These included, for example, where the coating could dissolve at different pH levels due to the variations in the pH of the stomach, which pH could be influenced by food intake, including by the ingestion of alcoholic beverages. Furthermore, it was stated that variations in pH levels would affect the rate at which the coating dissolved and released the API. The witness considered that an enteric coating was a “more complex formulation exercise” and that the known problems of variability arising from enteric coating would have led him to explore all other formulation possibilities thoroughly, rather than “resorting to enteric coating”. Accordingly, he considered that it would have been obvious to form a non-enteric coated formulation containing an acid–labile API and that other approaches would be investigated, including immediate release formulations, where satisfactory bioavailability could be obtained.

In order to counter this evidence, it was argued by the Patentee that the same witness had previously come to the opposite conclusion in 1998, where he considered that it would be obvious to use an enteric coating on acid-labile API formulations, in that case in relation to the drug, omeprazole. Back then, the witness stated that the API “must be protected from the gastric juices of the stomach” and furthermore, that “an enteric coated dosage form would have been ideal, because once the dosage form had passed the stomach, the omeprazole would dissolve rapidly and be bio-available”. He also added that an enteric coating would be formed using conventional coating techniques.

The inconsistency of the evidence given during this trial, when compared with that given earlier, resulted in Justice Jagot considering the evidence “to undermine the weight which would otherwise be given” to it.

In addition, the fact that the witness had acted as an expert witness in around ten previous Patent Proceedings during his career, would make him a veteran or professional witness, or possibly even a “gun for hire”.

The take-home lesson from this case is that it would be prudent for practitioners, prior to engaging an expert witness, to consider performing a thorough background and history check in relation to possible inconsistent statements or views previously expressed by the witness, so as to ensure that he/she remains credible in the eyes of the Court.