Under English law, legal professional privilege permits a civil litigant or a defendant in criminal proceedings to withhold from the other side documents subject to the privilege. However, privilege will not apply when a person consults a lawyer to further any criminal or fraudulent purpose, regardless of whether the lawyer is aware of the purpose.
A recent judgment in the long running dispute between the Kazakh bank JSC BTA Bank and its former chairman Mukhtar Ablyazov provides an insight into the so-called "fraud exception" to privilege. The full facts of the case and commentary can be found in my article, which can be found here, but the test in substance appears to be a question of the egregiousness of the alleged iniquity or fraud. The Court acknowledged that this would often be "a question of fact and degree". In this case, privilege was held to not to apply to certain communications between Ablyazov and his lawyers that related to his current and former assets. This is perhaps not surprising when the Court found that from the beginning, Ablyazov "was bent on a strategy of concealment and deceit in relation to his assets which would involve perjury, forgery and contempt as and when such was required for that purpose".