O’Melveny & Myers and its lawyers at Gibson, Dunn & Crutcher are set to square off in federal court next month over claims that O’Melveny bungled its nearly decade-old representation of a now-bankrupt client.

At stake is a $54 million claim from Jeffrey Golden, a partner at Weiland Golden Goodrich who is the Chapter 7 trustee overseeing the estate of Aletheia Research and Management. Golden claims that O’Melveny and two of its lawyers, Steven Olson and Jorge deNeve, mishandled a legal battle Aletheia had with Proctor Investment Managers, another investment firm, that began in late 2009.