A federal judge in Tucson blocked the state Tuesday from enforcing Proposition 200, at least for the next three weeks. U.S. District Judge David Bury granted a temporary restraining order after concluding that lawyers hired by the Mexican American Legal Defense and Education Fund raised "serious questions" about the measure's legality. "It seems likely that if Proposition 200 were to become law, it would have a dramatic chilling effect upon undocumented aliens who would otherwise be eligible for public benefits under federal law," the judge wrote, although the language of the initiative specifically exempts programs mandated by federal law. Tuesday's decision is not the end of the matter. Bury scheduled a full-blown hearing for Dec. 22 to determine whether to enjoin enforcement of the law until its merits and legality can be fully litigated - a process that could take months, if not longer. The judge stressed that Tuesday's ruling does not mean he accepts arguments by initiative foes that it is illegal. He said it shows only that he "lacks sufficient information at this time" to decide its constitutionality. Bury's ruling bars the state from enforcing the part of Proposition 200 that requires applicants for "public benefits" to prove they are in this country legally. The same section also says government workers must report illegal entrants to federal immigration authorities or face possible jail time and fines. The measure, approved by Arizona voters by 56-43 percent Nov. 2, was supposed to take effect today after Gov. Janet Napolitano signs a formal proclamation of election results. The Mexican American Legal Defense and Education Fund, or MALDEF, chose to file its challenge in Tucson because of its significant Hispanic population, the fact that Pima County voters rejected the initiative and the escalating number of people reporting that they are being denied some services, said attorney Steve Reyes. The Tucson human-rights group Coalición de Derechos Humanos has documented more than 120 complaints from U.S. citizens and illegal immigrants saying they've been denied services or fear they will be because of Proposition 200, said co-chairwoman Isabel Garcia. She declined to identify them because of the pending legal action. "There's been misapplications of Prop. 200 already," Garcia said. "And there is also an incredible amount of fear on behalf of the state providers as well as the people who need those services." The plaintiffs include some "undocumented" residents, who are listed only by first name and last initial. Attorney Hector Villagra, who argued for the restraining order, said they fear trouble if they send their undocumented children to school. Federal law specifies that legal presence in this country is not necessary for education. Villagra said other plaintiffs are here illegally but have children who are U.S. citizens who might not apply for health and welfare benefits, or even get emergency care, for which those children are eligible. There also are two public employees, one who works for the Department of Economic Security in Pima County and the other a Phoenix firefighter, both of whom say they are unsure what services they can and cannot provide under Proposition 200. Villagra said the Los Angeles-based MALDEF - which helped defeat California's similar Proposition 187 about a decade ago - was pleased with the judge's decision. "It will help ease some of the confusion that seems to be rampant out there," he said. Villagra argued that the initiative illegally forces state eligibility workers to screen for illegal entrants, "and not for the purpose of benefits eligibility." "We know that because there is this reporting provision that has absolutely nothing to do with eligibility for benefits," he said. "State employees will be, on their own, making determinations of whether federal law has been violated and reporting those violations to the federal government." He said that's something state workers are not trained to do. "This shows the purpose is to detect, report and effect the deportation of people in this country," which is solely the purpose of federal immigration officials, Villagra told the judge. Attorneys for the state argued unsuccessfully that a restraining order is legally inappropriate. "We have a law that voters approved," said Assistant Attorney General Mary O'Grady. "The state ought to be able to implement that." O'Grady said there is no real potential for harm. She pointed out that Attorney General Terry Goddard concluded last month that Proposition 200 is limited to a handful of benefits such as rental and housing assistance. O'Grady said people who would be denied those services under the initiative already are ineligible under U.S. law. Villagra, however, said Goddard's opinion is not binding. Randy Pullen, chairman of the Yes on 200 Committee, said he was not surprised by Tuesday's order. He said judges often want time to explore the legality of complex issues before letting new laws take effect. But Pullen, who intends to try to intervene in the Dec. 22 hearing, said the law eventually will be upheld. "I'm pretty comfortable where we are in constitutional law, and I still think we'll prevail," he said. Left untouched in Tuesday's ruling are sections of Proposition 200 that mandate proof of citizenship to register to vote and presenting identification when casting a ballot. Anti-200 attorney Daniel Ortega said there was no need to seek a restraining order for that part of the law because it cannot take effect until it is reviewed by the U.S. Justice Department. In a separate development Tuesday, a group led by state Rep. Ben Miranda, D-Phoenix, set up a toll-free number for people to report, in Spanish or English, problems due to Proposition 200. The number is 1-877-252-7555. Miranda, a foe of the initiative, said the information gathered could be used to file legal briefs in this case to convince a judge of the detrimental effects of the initiative.