The partners at the law firm of Quinn Emanuel Urquhart & Sullivan concluded a few years ago, before the financial crisis, that there was simply too much competition for representing major banks. So they decided to find some elbow room. The Los Angeles-based company would get out of the business of representing big banks and accounting firms and gear the work toward companies suing those institutions. “There weren’t many, if any, prestigious law firms who were willing to be adverse to these global financial firms,” said William Urquhart, a partner at Quinn Emanuel.