"QUESTION: I discussed my case with my attorney in a restaurant, loud enough for other diners to overhear me. Can they testify to what I said?
ANSWER: Yes. Lawyer-client communications are confidential only if they are made in a context where it would remain confidential. A defendant who talks to a lawyer in such a loud voice that others overhear what is said has no reasonable expectation of privacy and thus waives (gives up) the privilege. Similarly, people who talk about their cases on cell phones in public places risk losing confidentiality." -From, "The Criminal Law Handbook" By: Bergman & Barrett