A decision was given by Aldous LJ in the appeal by Smithkline Beecham against the decision of the Patents Court rejecting a claim of infringement of UK patent 2297550 against Apotex.
The case concerned the production of paroxetine hydrochloride anhydrate for the treatment of depression. The manufacture of the anhydrate results in impurities binding to the anhydrate crystals that include organic solvents used in the manufacture. The patent claimed a process for the removal of this bound solvent using a displacing agent , which causes the impurity to leave the substance but does not itself become irretrievably bound to the substance. Water can be used as such an agent and be removed by conventional drying techniques.
The prior art included an example that purported to show the production of the anhydrate including the use of "more" organic solvent to dissolve the substance and a subsequent final washing step using water. Later experiments showed that interpreting "more" as a small amount would produce the hydrated form (SmithKline Beecham’s argument).
On the other hand, Apotex argued that the skilled man would use several litres of organic solvent. The submission that this prior art destroyed novelty was rejected since the directions were not "clear and unambiguous". However, Apotex also argued alterations, by the skilled man, of a known experiment leading to the substance being produced made the claim obvious.
Apotex performed experiments with large quantities of organic solvent but introduced other conditions including carrying out the experiment under nitrogen to prevent the introduction of water. At first instance the judge accepted these alternatives to the experiment as detailed in the prior art. However, the Court said that this was an error of principle as there was no evidence a skilled man would use such dry conditions.
Aldous LJ was of the view that such experiments should be performed by a skilled man without the direction of lawyers to avoid inevitable hints being given to the scientist. What the Court required was performance of the unembellished disclosure. He suggested that in the future a court -appointed expert should be used and consulted when leave to adduce experimental evidence was requested.
Court -appointed experts are not widely used in the UK but were provided for in particular to reduce costs to individual parties. However, this proposal would result in difficult case management as the Court would need to hear submissions on the precise nature of the science in dispute and make a decision itself that inevitably would be open to appeal.
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