At least a violation of the Prime Directive. He is abrasive with Kirk:Fox should be brought up on some sort of charges.
KIRK: Code seven-ten means under no circumstances are we to approach that planet. No circumstances what so ever.
FOX: You will disregard that signal, Captain.
KIRK: Mister Fox, it is their planet.
FOX: Captain, in the past twenty years, thousands of lives have been lost in this quadrant. Lives that could have been saved if the Federation had a treaty port here. We mean to have that port and I'm here to get it.
KIRK: By disregarding code seven-ten, you might well involve us in an interplanetary war.
FOX: I'm quite prepared to take that risk.
KIRK: You are. I'm thinking about this ship, my crew.
FOX: I have my orders, Captain, and now you have yours. You will proceed on course. Achieve orbit status and just leave the rest to me. You're well aware that my mission gives me the power of command. I now exercise it. You will proceed on course. That's a direct order.