The 24th Amendment, ratified in 1964, outlawed the use of this tax (or any other tax) as a pre-condition in voting in Federal elections. The 1966 Supreme Court case Harper v. Virginia Board of Elections extended this explicit enactment as a matter of judicial interpretation of a more general provision, ruling that the imposition of a poll tax in state elections violated the Equal Protection Clause of the 14th Amendment to the United States Constitution. (This is one of several quizzical rulings that rely on the Equal Protection Clause of the 14th Amendment rather than the more direct provision of the 15th.)
I sispect the Arizona law will be similarly challenged in Court.
Prop 200 was very carefully written and even with McCain coming out against it all over the state, it passed with a large majority. I understand Colorado is working on getting their own proposition on the ballot based on our initiative.