Most people understand that when they have a private conversations with their lawyers about an existing or potential case, whether criminal or civil, those conversations are supposed to remain confidential. This is referred to as the attorney-client privilege, and it means that no one can compel the attorney or the client to disclose what was discussed between them.
However, in the context of a pending case or investigation involving a corporation and its executives or employees, it may not be clear who exactly the attorney represents. For instance, in a recent federal criminal case, the government was investigating a company and its chief financial officer for conspiracy and securities fraud. The company hired a lawyer to assist with an internal investigation and an audit. That lawyer interviewed the CFO who gave that lawyer important information critical to his own case. The CFO believed that the lawyer was his lawyer and all communication between the two was confidential and private. This particular attorney had even represented the CFO in the past in civil cases, which further led the CFO to believe that he was having confidential discussions with his personal lawyer.
Subsequent to those conversations with the CFO, the lawyer disclosed information from those conversations to other lawyers and accountants assisting in the internal investigation of the company and ultimately to the government. The government then intended to use that information against the CFO.