Which portion of 'international law' allowed the King of Saxony to be imprisoned and half his country taken? Further, which 'article' of international law allowed Russia to absorb the Duchy of Warsaw? Who legislated that it was 'legal' to force Belgium and Holland into a union to form a new country? Why wasn't the Kingdom of Italy allowed to remain an independent nation instead of being reabsorbed by Austria? By what right was the Rhineland ingested by Prussia?
Seems to me what is being stated is that it was all right for the allies to do what they chose to do after they won in 1814, but it was 'illegal' for Napoleon to do the same thing after his victories.
Sincerely,
Kevin