JAG - Season 5 Episode 12
Into the Breech

Harm and Mac stumble upon a miscarriage of justice in a 10-year-old case when they tutor a group of law students in a mock trial. In the original case, an investigation team headed by Admiral Chegwidden concluded that a disgruntled gun captain caused an explosion that killed 29 sailors, including himself. But when the ""defense attorney,"" helped by Mac, and the ""prosecutor,"" helped by Harm, retry the case, a new witness and new evidence are uncovered, prompting Mac and Harm to request that the original hearing be re-evaluated.