Jesse James DeConto has an excellent overview of the Secure Communities Program, the federal anti-illegal immigration effort that turns local police into enforcers of federal immigration laws:
Because they lead to incarceration, 287(g) and Secure Communities effectively criminalize immigration violations, which the U.S. had historically handled as civil matters in special administrative courts. Immigration courts, crucially, are not bound by the same rules as criminal courts. Suspected illegal aliens do not have an absolute right to an attorney: The government can't stop them from hiring a lawyer, but they can't fall back on a public defender. Nor do they have a right to see exculpatory evidence. Judges can allow hearsay and illegally obtained evidence. To make its case, the government has to provide “clear, unequivocal and convincing evidence,” not the proof “beyond a reasonable doubt” required in criminal cases. Hence an immigrant like Gomez can be deported even with only doubtful evidence that he entered the country illegally, and even if the police never should have approached him in the first place. Nor can he count on the immigration courts to protect what limited rights he has. According to the American Bar Association, immigration judges apply the law inconsistently and the Board of Immigration Appeals “unduly favor[s] the government at the expense of the noncitizen.”
This way, the federal government has it both ways--they can treat immigration violators as criminals but without extending to them the protections offered to criminal defendants. Despite the Obama administration's rhetorical objections to Arizona's SB 1070 suggesting the law would encourage police to engage in racial profiling, the same incentives encouraging profiling are present here. In participating jurisdictions, police know that the biometric identifying information of arrestees will be forwarded to Immigrations and Customs Enforcement, so even if the person in question isn't dangerous, they can be arrested on a pretext and if they're in the country illegally, they can then be detained by immigration authorities.
Secure Communities doesn't possess all the other aspects of draconian immigration laws that basically criminalize all aspects of life for the undocumented--everything from attending school to giving undocumented immigrants rides--but it certainly offers an example of cognitive dissonance on the part of administration officials who have expressed concern over the possibility that SB 1070 would lead to "racial profiling." The simple answer is that the administration is less concerned about racial profiling than it is about federal preemption and the possibility of states forming their own immigration laws.