Arizona Tax Credit Case

I. Arizona provides a dollar-for-dollar tax credit for contributions to school tuition organizations (STOs)

        ---tax credit of $500 per individual or $1000 per married couple
        ---these tax credits are very popular with an estimated total of $50 million per annum
        ---STOs are non-profits that use these contributions to fund scholarships for students attending private schools, many of which are religious
         ---Respondents sued as taxpayers who claim that the tax credit program violates the Establishment Clause

II. Taxpayer Standing: Do state taxpayers have Art. III standing to challenge a tax credit program such as Arizona's in federal courts?