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Freshfields Risk & Compliance

| 3 minutes read

Stay of execution? Mylan can challenge Neurim’s divisional backup in the UK, but only just

Meade J has held that Mylan can seek to invalidate Neurim’s divisional patent in infringement proceedings brought against it in the UK, in the latest chapter of the complex Neurim v Mylan dispute.

However, the preliminary issues hearing was not determinative. The case has been transferred back to Marcus Smith J, who held the extremely similar claims of the parent patent valid (before that patent was finally revoked by the EPO), on the basis that he may be in a position to adopt his previous judgment rapidly, and decide whether Mylan should be able to appeal that judgment prior to expiry of the patent in August.


Neurim Pharmaceuticals Limited (Neurim) is the patentee of EP (UK) 3,103,443 (EP 433). EP 433 protects Neurim’s product, Circadin, which relates to the use of melatonin for the treatment of insomnia. Mylan wishes to sell its generic competitor in the UK.

EP 433 is a divisional of EP (UK) 1,441,702 (EP 702). In previous UK proceedings, Neurim sued Mylan (now Viatris) for infringement of EP 702. In those proceedings, heard by Marcus Smith J, EP 702 was held valid in the UK, and infringement was admitted by Mylan.

Following judgment, Neurim sought to obtain a final injunction promptly. Given the absence of an interim injunction, the launch of Mylan’s generic product in the UK, and the upcoming patent expiry, an early hearing of consequential matters was fixed for 16 December 2020. The Orders made included an injunction and delivery up, and refusal of permission for Mylan to appeal on validity.

On 18 December 2020, only two days later, the patent was revoked at the EPO, and on 30 December 2020, Marcus Smith J revoked the material parts of his 16 December Order. A further consequentials hearing followed in February 2021.

EP 433 was granted on 30 June 2021, and Neurim initiated infringement proceedings against Mylan in the UK on the same day. In these proceedings, Neurim applied to amend the claims of EP 433 to a form “patentably indistinct” from those of EP 702.

Meade J was tasked with determining the following preliminary issues:

  1. whether Mylan is issue-estopped from challenging the validity of EP 433 in the light of the 2020 action;
  2. whether Neurim’s conduct in amending the claims of EP 433 to mirror those of EP 702 is an abuse; and
  3. whether Neurim’s conduct, in particular:
    • withdrawing its EPO appeal to avoid a written decision in relation to EP 702 affecting the prosecution of EP 433; and
    • seeking to rely on issue estoppel to prevent an effective appeal in the UK, 

amounts to an abuse of a dominant position.

Yesterday’s judgment

In relation to each of the three issues, Meade J held:

1. No issue estoppel

  • Prior to revocation at the EPO: The December 2016 Orders were provisional, pending the result of the EPO hearing, which ultimately resulted in them being revoked. These Orders therefore lacked the finality required for issue estoppel.
  • After revocation at the EPO: Mylan was the “winner” and could not therefore appeal the decision on validity. There could therefore be no issue estoppel.

2. Claim amendments not abuse

  • It was not alleged that using a divisional as a backup was itself an abuse.
  • The form of the amended claims, and their degree of similarity to other patent claims, did not give rise to an abuse.

3. Competition issues not decided

  • Competition law arguments were not determined for the following main reasons:
    • legal questions were complicated and required developments in the law;
    • additional factors/issues may have needed to be considered to reach a decision;
    • further consideration would have led to a delay to the judgment; and 
    • in light of the issue estoppel decision, it was unlikely that they had any practical significance. 

What’s next?

The case has been transferred back to Marcus Smith J to consider:

  • whether the EP 702 judgment should be adopted, in light of additional invalidity arguments raised at the EPO; and
  • whether Mylan should now have permission to appeal the judgment.

Other takeaways

For cases where there are parallel national and patent office proceedings, the timing of hearings is often a strategic decision for the parties. Whilst this case is unusual on the facts, it is a reminder of the importance of co-ordination between the different legal teams. It also makes clear that the UK courts expect to be actively kept informed of any scheduling issues and changes at the EPO.


intellectual property, life sciences, litigation