Nicholas Mendoza looks at why the Obama administration has relied on arguments that the federal government has the authority to set immigration policy instead of challenging immigration laws on racial profiling grounds:
Tumlin argues that the substantive differences between the two complaints have a lot to do with who the plaintiff is in each case. For example, while the Justice Department includes the challenge to the K-12 schooling provisions of the Alabama law (which require records be kept on undocumented children enrolled in Alabama schools), it does not challenge the law's ban on undocumented students enrolled in public universities. The civil rights groups' complaint (PDF) does, but Tumlin argues that it can do so more easily because some of the plaintiffs in their lawsuit are college students, teenagers planning on going to college or adults who are enrolled or plan to enroll in ESL classes at community colleges.
Sam Brooke, a staff attorney with the Southern Poverty Law Center, says that the reason for the difference between the two lawsuits is that while the federal government naturally has the strongest claim when it comes to preemption, civil rights groups and individuals are best positioned to sue over civil rights violations.
I think this is basically right. Attorney General Eric Holder or President Barack Obama's personal feelings about racial profiling aside, preemption is really the strongest legal basis on which to file these challenges, and that's why this is the approach they've chosen in fighting draconian immigration laws in the states. It would be a mistake to assume the challenges represent lenience on the administration's part, given that it has been deporting undocumented immigrants at a faster rate than the previous administration and, despite periodic conservative freakouts over "de-facto amnesty," has actually been stingier than Bush in granting deferrals. The Obama administration isn't squeamish about deporting people. They just want it done their way.
This is true in general--but it's mind-blowing how far the conservative perception of Obama administration policies is from actual reality.