Excellent point. Kerry earned his JD at Boston College Law School in 1976 and was was admitted to the Massachusetts Bar later that year. Now I do not know about Massachusetts but in California, in order to become a member of the bar, you must pass a "Determination of Moral Character." This involves a huge application 27 pages long. Page 17 states "If you are now separated from military service, attach a copy of DD Form 214 to the application."
Concievably the Massachusetts Bar has information on this, as well as the Middlesex County District Attorney's Office where he first worked. Fat chance of either of them cooperating on this though.