You're right. That notwithstanding, it would be a blast to watch the UN try.
UN guy: "So would you please sign our treaty and subject yourself to our international court?"
Texas guy: "Do you even know who you're talking to? This is Texas! We do whatever the **** we want!"
UN guy: "Well, um, I mean..."
Texas guy: "Here, give me that treaty." *crumples it up and eats it*
UN guy: "Umm... well....... think about it."
Texas guy: "Yeah, we'll do that."