One of the most blatant Kirk violations, that I never hear lip service given to is "Friday's Child". The Klingon hadn't interfered. He was offering an alliance, but he didn't provide arms or men. Maab's coup seems completly within his culture's boundries and Kirk sticks his nose in. The result is EXACTLY* why the PD exists.
Of course, alls well that ends well.
*Eleen: "I was prepared to die, kill him as well!" Good job, Kirk.
I suspect these pre-warp TOS contact CF's are exactly why the Feds changed their first contact rules.