You are correct, Breyer on SCOTUS probably wouldn't, but Scalia and Thomas would.
Look who cares that the Mexican govt. is trying to overturn Prop. 200, they can't, the people who will try to overturn it would be a Clinton/Carter packed 9th circus court in San Francisco.
I think we should care when Mexico starts writing it's stupid comic books, fails to support us with the war in Iraq, condemns the voters of America for not wanting to do what the Mexican government has never wished to do for it's citizens.
The whole massive immigration problem originates in that corrupt but wealthy country and that's where the best fix can take place. It's not going to get fixed until we actually stand up and tell them it's time to get it done because we're not going to continue this.