Bristows wins for Smith & Nephew in Patents Court battle on limits of numerical ranges

The Patents Court has handed down its judgment in Smith & Nephew v ConvaTec No.2. Bristows acted for the successful claimant, Smith & Nephew, in the most recent instalment of litigation involving ConvaTec’s patent for silverised wound dressings (silver being known for its healing properties).

Following an earlier revocation action brought by Smith & Nephew, ConvaTec’s patent was upheld in amended form due to a limitation requiring one of the reagents to be present in a concentration of ‘between one and 25 per cent’.

The recent decision confirms that a process developed by Smith & Nephew that uses a concentration of 0.77 per cent does not infringe. Further, the court concluded that ConvaTec is not entitled to a springboard injunction preventing Smith & Nephew from launching dressings produced by that process.

In deciding to grant Smith & Nephew a declaration of non-infringement for its 0.77 per cent process, the court has reiterated that the scope of numerical ranges in a particular claim cannot be considered in isolation and is instead fact dependent. This will be of interest to all patentees with claims that include numerical ranges as it confirms that the rounding of values to the number of significant figures expressed in the claim is generally accepted scientific convention, and an approach likely to be adopted in the absence of evidence or a patent specification suggesting the contrary.

Liz Cohn, partner at Bristows, represented Smith & Nephew.