IANAH, but this runs counter to my understanding. The Opium Wars are closer to what we are currently fighting, than to the results of legalization. The British (Mexico) wanted to sell opium to the Chinese (US) when it was against Chinese (US) law. There is a significant difference in that Mexico technically forbids this activity too, of course, while the British did not, but legalization by the US would move it further away from the historical situation, not closer to it.