Regeneron Hybrid Mouse Patents Called Invalid By Top U.K. Court

Regeneron Pharmaceuticals Inc. lost a patent fight with a British biotech company on Wednesday, when the U.K.’s highest court invalidated two of its patents on genetically modified mice.

Overturning a lower court ruling, the U.K. Supreme Court found New York-based Regeneron’s patents are invalid because they don’t adequately explain how to make all the different types of mice that it claimed to have invented.

The ruling illustrates how U.K. courts should interpret a bedrock rule in that country’s law that requires a patent be detailed enough to allow an expert to make the invention. It also serves as a reminder ...