I see more and more cases with service members who have either PTSD and/or TBI committing offenses that they undoubtedly would not have committed prior to their injury. Unfortunately, in many of these cases PTSD and/or TBI are not a "defense" in that don't negate a person's criminal liability at a court-martial. Still, it can be very useful evidence in either convincing the government to refer a case to court-martial, or in "mitigation" evidence in the event of a conviction. Here is a very interesting article I came upon that discussed this issue in great detail, albeit mainly in the civilian court context

Grey, Betsy J. Neuroscience, PTSD, and sentencing mitigation. 34 Cardozo L. Rev. 53-105 (2012).

This recent law review article traces the use of PTSD to mitigate sentences. It's comprehensive coverage of theory and success or failure of this mitigant is useful reading for any practitioner, particularly in military courts, where the argument may have special resonance.
The author also discusses in detail recent advances in neuroscience that may in time enhance the persuasive force of an argument that PTSD affected the behavior of an offender.

If you or a loved one need a court-martial attorney or a court-martial appeals attorney, contact me for a free consultation.