Three Court of Appeal cases (the two below and Samsung v Apple discussed here) and one first instance case have considered revocation of patents on the basis of an invalid claim to priority and consequent invalidity over intervening pieces of prior art.
Hospira and Generics (trading as Mylan) v Novartis  EWCA Civ 1663, Court of Appeal
Novartis's patent related to the use of a bisphosphonate known as zolendronate for the treatment of, amongst other things, osteoporosis.
The issue arose in the context of proceedings brought first by Hospira UK Limited and then also by Generics (UK) Limited (trading as Mylan) for revocation of the patent. Both companies wished to market products falling within claim 7 of the patent.
Claim 7 contained a combination of features directed to
- the drug
- the fact that the drug was intended for the treatment of osteoporosis
- the mode of administration (intravenous)
- the range of dosage sizes (2 - 10 mg) and
- the dosing interval (about once a year).
Arnold J held that the claim to priority for claim 7 was invalid and as a consequence of that loss of priority, claim 7 was invalid over a disclosure in an intervening publication. Novartis appealed only in relation to the Judge’s finding that claim 7 of the patent was not entitled to claim priority. It was conceded that claim 7 would be invalid if it was not entitled to claim priority because of the disclosure in the intervening publication.
The Court of Appeal dismissed the appeal. They held that
Put in a nutshell, the problem for Novartis in seeking to establish that claim 7 is entitled to priority from 'the priority document' is that the disclosure of the 'priority document' is either too general or too specific. If one focusses on the disclosure about zolendronate, the '2 - 10 mg once a year' passage tells the skilled reader nothing about dosage range for any particular method of administration. It also does not tell the reader about the dosage range for any particular condition, such as osteoporosis. It teaches that 4 mg, once a year, administered intravenously to patients with post-menopausal osteoporosis is effective but nothing about what other doses could be used at that dosage interval.
The Court found that the expert evidence adduced at the trial did not displace their view that there was no disclosure in the priority document of once a year dosing by intravenous administration to treat osteoporosis. Therefore the Court of Appeal held that the invention in claim 7 was not disclosed in the priority document and as such was not entitled to claim its priority date.
Read more on the "Invalid Claim to Priority"
HTC Corporation v Gemalto S.A.  EWCA Civ 1335, Court of Appeal
Nestec SA & Ors v Dualit Ltd & Ors  EWHC 923 (Pat), Arnold J.