13 August 2015
This was the question posed in Smith & Nephew’s application for a declaration of non-infringement for their silverised wound dressing.
When considering the question, ‘What is the true construction of “between 1% and 25%”?’, at first instance, Mr Justice Birss applied the ‘significant figures’ approach. It was determined that the range “1-25” means “0.95-25.5” and does not include 0.77, thus concluding no infringement. The Court of Appeal disagreed, however, and used a ’rounding-up’ approach to determine that “1-25” means “0.5-25.5”, thus concluding infringement.
This decision presents interesting options when drafting a patent application, and careful consideration should be taken when choosing the number of significant figures provided in the description. In prosecution it seems that simply reciting a lower limit of e.g. “1” in a claimed range where there is basis for reciting “1” or “1.0”, might provide broader claim scope.
In opposition, there might be potential added-matter issues if a claim recites a lower limit of e.g “1.0”, and there is only basis for a lower limit of “1”. If a range with a lower limit of “1” indeed is a broader range than one with a lower limit of “1.0”, it would be impermissible to amend “1.0” to “1”, and it may therefore not be possible to remove the added-matter without significantly limiting the claimed range.
The full decision can be found at: http://www.bailii.org/ew/cases/EWCA/Civ/2015/607.html
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