For those who try to physically breach a client's offices, a wrong turn can lead to an encounter with security, so most carry a "get out of jail free" letter from the client.
So defense lawyers first provide the name and Social Security number of a client to the criminal division of the IRS, and are given a green or red light for the program.
So in an elaborate dance, defense lawyers first provide the name and Social Security number of a client to the IRS, and are given a green or red light for the program.