Data-mining class actions against Silicon Valley’s tech heavyweights will rage for years. But plaintiffs lawyers looking for a big payday are facing major obstacles, thanks in no small part to Cooley partner Michael Rhodes, a go-to litigator for Google Inc. and Facebook Inc.

Rhodes scored a major victory on Wednesday, when U.S. District Judge Lucy Koh in San Jose effectively blocked claims that Google’s approach to data privacy violates wiretap laws. In a 41-page ruling, Koh refused to certify a proposed class action on behalf of various categories of Google customers, including Gmail users, alleging that their communications were improperly intercepted by Google for the purpose of formulating targeted advertisements.