Switzerland’s Federal Supreme Court has ordered a fresh ruling in the case of three men accused of breaching Swiss bank secrecy laws by leaking data that helped expose the cum-ex tax fraud scandal, one of the largest financial crimes in European history.

The three defendants, unnamed in the court documents, were convicted in 2019 on charges including banking espionage and violation of banking secrecy. That verdict was overturned on appeal in 2021. After years of further litigation, the Zurich High Court ultimately dropped the case altogether, citing excessive procedural delays and finding that the investigating prosecutor had shown bias. Following an appeal by the Zurich Public Prosecutor’s Office, the Federal Supreme Court has now remanded the matter to the lower court, ruling that neither the delays nor the alleged bias justified terminating proceedings.

German press agency DPA identified one of the defendants as Stuttgart lawyer Eckart Seith, who faced charges after providing German authorities with Swiss bank documents that triggered investigations into illegal cum-ex transactions. Two former German employees of Bank J. Safra Sarasin were also reportedly charged in the same case.

Swiss banking secrecy legislation criminalises the disclosure of confidential client information by bank employees or third parties, and contains no exemption for those exposing wrongdoing. The cum-ex scheme itself involved rapid share trading around dividend payment dates, structured to obtain refunds for a tax that had been paid only once. German authorities eventually halted the practice, which experts estimate cost the treasury as much as 12 billion euros. Seith told DPA that investigating serious crimes is protected under European legal order, adding that he did not expect Switzerland to place itself outside that framework.