You may have read in the last few days that Kerry finally signed Form 180 to allow the complete disclosure of his military records. Turns out Kerry received numerous very glowing commendations with some from officers who later criticized his military service.
That he did not release this information last August is probably why is not now President. The only thing that I can think of to explain Kerry's refusal to release the full file is principle. The campaign should not be about what he did 35 years ago, giving in to these kinds of demands for more and more info from the distant past only encourages further digging, and scandal mongering, yada, yada, yada.
I could write a good deal about what I think about Kerry's position (that resoundingly silencing the SB Liars imunizes you from further digs into your distant past) but it would really be pointless now.
I like the CJR view of this story so I'm suggesting you go read it.