Two former Eversheds partners have accused the firm of operating illegally in France as they claim unfair dismissal.
Eversheds has called in top French firm Bredin Prat to defend the claim.
Two female partners claim the firm’s structure has not been approved by the Paris Bar.
Eversheds gained its Paris arm when it merged with Frere Cholmeley Bischoff in 1998.
In the UK the Frere Cholmeley name disappeared, but it is maintained in Paris, where partners are officially in partnership at Freres.
The former partners claim that this was never approved and that the firm did not notify the bar when it converted to a limited-liability partnership in May 2003.
Additionally, it is alleged that Eversheds is in breach of bar rules by not having a French avocat as managing partner.
The parties are currently involved in arbitration. The former partners are being advised by Cournot partner Laurent Paris. Both Paris and Eversheds declined to comment.