Regeneron Pharmaceuticals Inc filed patents for a new type of genetically modified mouse which was a hybrid version of the gene that produces antibodies, combining a section of the mouse’s genetic material with a section of the genetic material from a human. In 2013, Regeneron sued Kymab Ltd for infringements of its patents. Kymab was producing its own genetically modified mice, with a similar genetic structure to Regeneron’s mice. Kymab argued that the patents filed were invalid because they fell foul of a patent law rule called sufficiency which means that documents filed with the patent must be detailed enough to enable scientifically skilled readers to make the invention for themselves. The Court of Appeal upheld the patents and Kymab appealed to the Supreme Court.

The Supreme Court allowed Kymab’s appeal by a majority of four to one, holding that the patents are invalid. Regeneron’s patents did not enable a skilled person to make mice containing more than a very small section of the human variable region. The amount of human material was an important factor which was thought to affect the diversity of useful antibodies which the mice would produce. Mice at the more valuable end of the range could not be made using Regeneron’s patents. So Regeneron was claiming a monopoly which was far wider than its contribution to the art. The Court of Appeal’s analysis had watered down the sufficiency requirement which is a bedrock of patent law, tilting the balance of patent law in favour of patentees and against the public.

For judgment, please download: [2020] UKSC 27

For Court’s press summary, please download:  Court’s Press Summary

For a non-PDF version of the judgment, please visit: BAILII

To watch the hearing please visit: Supreme Court website 11 February 2020 morning and afternoon session and 12 February morning and afternoon session

To watch the judgment summary, please visit: Supreme Court website: 24 June 2020