Probably the most efficient method would be to force all the binders into unbreakable oaths not to rebel. You are, of course, still losing a significant portion of the total magical powers of the population by using unbreakable vows en-masse like this, and far from other countries seeing and wanting to copy this system, they're liable to see it as either an exploitable weakness or a human rights violation, in which case this society could be facing trade sanctions, embargoes, or even war.

Look at how effective those are in the real world. You have countries ignoring sanctions and embargoes because there's a lot of money to be made that way. As for wars with large coalitions, you have the inevitable issues of members suspecting other members of not holding up their end of the war, or using the war to unfairly increase their power vis-a-vis the other members of the coalition.

Of course, it's not hard to solve all these problems using unbreakable vows, but well. ;)