It's about imputed disqualification and whether screening (f/k/a "Chinese Walls") works in California. Here's the Court of Appeal's conclusion, which helpfully comes in the first paragraph:
"When an attorney obtains confidential information from a client, that attorney is prohibited from accepting a representation adverse to the client in a matter to which the confidential information would be material. In this case, we are not concerned with the issue of disqualifying the attorney possessing the material client confidences from representing an adverse party; it is conceded that the attorney is disqualified from doing so. Instead, we are concerned with the issue of the vicarious disqualification of the attorney's entire law firm. We conclude that, under the circumstances of this case, automatic vicarious disqualification is not required, and that, instead, there is a rebuttable presumption that the attorney's knowledge of client confidences is imputed to the firm, which can be refuted by evidence that the law firm adequately screened the attorney from the others at the firm representing the adverse party. In addition, as the disqualified attorney has left the firm, the trial court's examination of the screen's adequacy should be on a retrospective, not prospective, basis."
The opinion, which comes in at 55 pages, is pretty darn comprehensive. So all I'll add is one quasi-snide comment. The amicus brief on behalf of appellants is signed by a gazillion people, and might accurately be titled "Amicus Brief of Most of the Huge Law Firms In California, All of Whom Are Jonesing For PPP and None of Whom Want to Be Conflicted Out." The actual title, of course, is slightly different. Slightly.