Wilde Sapte is celebrating winning an arbitration case that will prevent more than two partners a year from quitting the firm.
Tom McDonald, a partner in the Paris office, had taken the firm to arbitration before a judge in France over the firm's constitution, which prevents more than two senior equity partners leaving in a 12-month period.
But the ruling has gone against McDonald, who hoped to join White & Case in Paris immediately. He will now have to serve out a notice period that could stretch for several years. It generally takes three to four years for senior partners to leave Wilde Sapte.
A queue of partners who have given notice to leave the firm were hoping a successful ruling would put pressure on the firm to let them go too.
Steven Blakeley, Wilde Sapte managing partner, says: "We are pleased with the result of the arbitration because it supports the view that the partnership arrangement we have is sustainable."
McDonald was unavailable for comment. But a source says: "Tom is feeling pretty down. I don't know what is going to happen to him now at Wilde Sapte. He will be stuck there for some time."
An insider at the firm says feelings are divided. Another source says: "This decision has caused great disappointment. I have read it and have a feeling it may be cultural.
"I have a feeling that he [the judge] felt the partnership agreement included a clause that said only two partners could leave when McDonald joined, so he should stick by it.
"That meant he would need a strong principle to override it. He was unable to convince himself that that existed."