SAN FRANCISCO — Munger Tolles & Olson is becoming Facebook’s go-to appellate counsel in big privacy class actions.

Munger partners Kristin Linsley Myles and Daniel Levin stepped in to represent Facebook before the U.S. Court of Appeals for the Ninth Circuit in a series of related appeals on Tuesday. The cases challenge a $20 million settlement of a class action over Facebook’s Sponsored Stories feature, which employed user names and likenesses to promote products and services.