What is the current state of the law with respect to the disclosure of confidential information to an opposing attorney?

In Brand v. 20th Century Ins. Co./21st Century Ins. Co. (2004) 124 Cal.App.4th 594, the court noted the evolution of a pragmatic approach. Under this approach, the attorney's possession of confidential information is presumed when a substantial relationship is shown to exist and when it appears by virtue of the nature of the former representation that confidential information material to the current dispute would normally have been provided to the attorney. (Id. at p. 603.)