Faced with a never-ending minefield of potential client conflicts, the occasional disqualification fight is part of doing business for big law firms in high-stakes business litigation.

For Munger, Tolles & Olson, the threat of disqualification is looming over a very different kind of case. In a pro bono matter for homeless and mentally ill clients in Los Angeles, Munger Tolles has found itself at odds with another former pro bono client that says the firm has betrayed its trust.