Mazur v Charles Russell Speechlys – will settled cases be reopened?

There have been a number of commentators suggesting that parties may start to reopen costs orders, or even judgments in the underlying litigation, in light of Mazur & Anor v Charles Russell Speechlys LLP [2025] EWHC 2341 (KB).

The arguments would presumably be either:

• the underlying claim/defence would have been struck out if it had been known that an unauthorised fee earner had unlawfully had conduct of the litigation; or
• the paying party would not have agreed costs or the court would not have assessed (whether by summary or detailed assessment) costs as they did if it had been known that an unauthorised fee earner had unlawfully had conduct of the litigation.

I struggle to see these arguments having much traction.

The important point is that Mazur did not purport to create new law. It was doing no more than clarifying the correct interpretation of the Legal Services Act 2007. It would always have been open to parties to take issue with unauthorised fee earners having conduct of litigation and/or seeking recovery of the costs of such work. The fact that parties historically did not take a good point (if that is what it is) would not be a reason to reopen settled litigation. Parties cannot argue ignorance of the law as a justification for having a second chance.