I have a question that may or may not apply. I hope Stephen or someone else can answer this...
I understand that with the changes in laws since 9/11/01, there are a host of Federal offenses that release the attorney from that part of the attorney/client privilege pact. My understanding is that almost anything that can be charged under 'Issues of National Security' would qualify.
If this is correct, than I guess the answer would be "as long as the family member's criminal activity is not a potential issue of national security"?