American combat veterans who served in OIF and OEF were diagnosed with severe neuropsychopathologies due to combat exposure and trauma. Studies on how combat exposure and trauma alter brain cortical structures were explored. The objective was to examine if combat veterans can remain on active duty or if they are predisposed to commit violent crimes was considered. However, limited data raised concerns about criminal responsibility for violent crimes. As evident, combat veterans with severe neuropsychopathologies do not meet personnel readiness standards, impacting military service obligations and national security operations. A systematic literature review included combat exposure effects and trauma on the brain. Data analysis processes were utilized using the PRISMA model to review pre-existing studies. Results revealed PTSD, mTBI, and depression comorbidities were leading neuropsychopathologies among combat veterans. Findings uncovered altered frontal lobes and anterior prefrontal cortex regions. Also, evidence showed combat veterans diagnosed with PTSD and depression were more likely to commit violent crimes. However, preliminary research could not determine if combat veterans are criminally liable, although they met the criteria for the insanity defense. Forensic neuropsychopathology identified the relationship between these conditions and the military legal system. Further research is recommended to examine severe neuropsychopathologies and affected brain regions through neuroimaging and advanced neuropsychological initiatives to improve mental healthcare practices within DoD.