“It is absolutely the case that, even if he is criminally liable himself, Michael Cohen is not allowed to disclose client confidences learned through the attorney-client relationship about any client without their permission,” said Paul Rosenzweig, a former legal adviser to Whitewater Independent Counsel Kenneth Starr.

Attorneys for Cohen and Trump declined to comment for this story. But other lawyers expect the president’s legal team would vigorously object to Cohen discussing Trump’s past dealings to prosecutors. Lawyers for Trump are already fighting in court to block prosecutors’ access to information that the FBI seized on the grounds that it is covered by privilege.

There are exceptions to what privilege will protect. Communications made with the intent of committing or concealing a crime or fraud are exempted, for instance.

And Cohen is entitled to disclose conversations with Trump that are directly related to charges he might face.