There are so many franchise episodes with a main character on trial, it's kind of funny when you think about it. Most of them work pretty well. I mean, there's a reason Perry Mason and all its descendants have been such a reliable TV tradition. Law makes good drama.
"Court Martial" might almost be said to be a slightly more original version of "The Menagerie," which was the earlier two-part episode that put Spock on trial while regurgitating the otherwise unaired original series pilot, "The Cage." Spock's trial was kind of beside the point in that story. Certainly anyone who watches that one now won't really think of it in that way.
So it makes sense that the series didn't really find it unnecessarily duplicative to put another main character on trial only about ten episodes later. The subject this time is Kirk. Kirk on trial became its own trope, thanks to the movies Star Trek VI: The Undiscovered Country (which itself was later echoed in the Enterprise episode "Judgment") and Star Trek.
I'm recommending this one most for Kirk. Since "Menagerie" technically got to the trial trope before "Court Martial," I'll keep that one as the key precedent. The story features more of Kirk's past coming back to haunt him, old colleagues with scores to settle, this time an old Academy instructor whom Kirk later caught in a mistake (so a little like Next Generation's "The First Duty," too) and ended up serving under him, of all indignities. The truth of what happened is revealed in the end to be that there was no death after all, just the guy trying to screw Kirk over like he feels he was. Same thing happens in later trial episodes.
But if there's any doubt that it's Kirk who is the lead character of the series, it's an episode like this one that comes along to make it clear.
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