In Texas, by any other name it's still a poll tax In 1964, the American people enacted the 24th Amendment, to prevent the exclusion of the poor from the ballot box. In his speech last week at the NAACP convention, U.S. Atty. Gen. Eric H. Holder Jr. wasn't indulging in election-year rhetoric when he condemned Texas' 2011 voter photo identification law as a poll tax that could do just that. He was speaking the hard legal truth. The Justice Department would be right to challenge this new law as an unconstitutional poll tax. The department has temporarily blocked the Texas law under special provisions of the Voting Rights Act that prevent states with a history of discrimination from disadvantaging minority groups. But the attorney general should go further and raise a 24th Amendment challenge against Texas and other states that are joining the effort to bar the poor from the polls. This exclusionary campaign should not be allowed to destroy a great constitutional achievement of the civil rights revolution. The 24th Amendment forbids the imposition of "any poll tax or other tax" in federal elections. Texas' law flatly violates this provision in dealing with would-be voters who don't have a state-issued photo ID. To obtain an acceptable substitute, they must travel to a driver's license office and submit appropriate documents, along with their fingerprints, to establish their qualifications. If they don't have the required papers, they must pay $22 for a copy of their birth certificate. If they can't come up with the money for the qualifying documents, they can't vote. But the 24th Amendment denies states the power to create such a financial barrier to the ballot box. Texas' violation is particularly blatant. In drafting its law, the Legislature rejected a provision that would have provided free copies of the necessary documents. Rather than paying for this service out of the general revenue fund, it chose to disqualify voters who couldn't pay the fee. This is precisely the choice forbidden by the Constitution. The 24th Amendment doesn't only invalidate the $22 tax. Texas also can't impose unnecessarily arduous certification procedures. The Supreme Court took up this issue shortly after the amendment was ratified in 1964. The state of Virginia had told its citizens they could avoid its $1.50 poll tax only if they filed a formal certificate establishing their residency. Lars Forssenius and others refused to comply, and a near-unanimous Supreme Court in 1965 agreed with them. Chief Justice Earl Warren wrote in the ruling that the state's administraton of its residency certificate requirement was a "real obstacle to voting in federal elections" that "abridged" the franchise. He emphasized that constitutional end-runs were not permitted. "For federal elections," he explained, "the poll tax is abolished absolutely as a prerequisite to voting, and no equivalent or milder substitute may be imposed." This broad functional view of taxation is firmly rooted in our constitutional tradition. In his recent opinion in the healthcare case, for example, Chief Justice John G. RobertsJr.adopted the same approach in finding that the "penalty" imposed by the Affordable Care Act was the functional equivalent of a tax. But in Warren's ruling, the same broad approach to taxation led to a very different conclusion. Unlike Roberts, Warren was not marking out the boundaries of congressional power. He was restricting the power of the states to impose unnecessary administrative barriers that were the functional equivalents of poll taxes. Applying Warren's approach to the present day has large practical implications. The estimated number of registered voters in Texas without valid IDs ranges from 167,000 (according to the state) to more than 1 million (according to the federal government). The Justice Department also emphasizes that minority groups are disproportionately affected. What is more, 10 other states have passed similar laws in the last two years alone. All these statutes raise fundamental problems under the 24th Amendment. Curiously, these problems have been overlooked in the escalating wave of challenges to this recent round of exclusionary legislation. Civil rights lawyers have focused instead on more familiar texts such as the Voting Rights Act and the 14th Amendment. Though these provisions are important, they were created in response to a host of other issues. The poll tax amendment, in contrast, was focused on the very problem that now threatens again to undermine our democracy: imposing costs on the poor that prevent them from voting. The attorney general was right to recall the amendment from legal obscurity, and to insist that we remember the determined effort by the civil rights generation to end this disgraceful practice forever. Bruce Ackerman and Jennifer Nou are coauthors of an article on the poll tax amendment in the Northwestern University Law Review. He is a professor of law and political science at Yale; she is an academic fellow at the University of Chicago Law School.