1163 will really give you an idea of the conditions and reasons for why he was discharged in 1978 with an Honorable. He had to have originally been characterized as separated under "other than honorable conditions" back in the early 70's.
so is it possible he resigned instead of a court martial and accepted an other than honorable discharge?
Here is the exact wording of Kerry's discharge for our archives off of the PDF. The Italicized parts were added for clarification purposes.
1) By direction of the President, and pursuant to reference (a)(10 U.S.C.S. 1162), you are hereby honorably discharged from the U.S. Naval Reserve effective this date (Feb. 16, 1978).
2) This action is taken in accordance with the approved recommendations of a board of officers convened under the authority of reference (b) (10 U.S.C.S. 1163) to examine the official records of officers of the Naval Reserves on inactive duty and determine whether they should be retained on the rolls of the Reserve Component or separated from the naval service pursuant to Secretarial instructions promulgated in reference (c) (BUPERSMAN3830300).
3) The Navy Department at this time expresses its appreciation of your past services and trusts you will continue your interest in the naval service.
http://www.johnkerry.com/pdf/jkmilservice/Honorable_Discharge_From_Reserve.pdf