Its pretty clear from this summary of the Obama administration legal brief that the Administration has no idea what its own immigration policy should be. I don't agree with all of the author's statements (for example, I am not a fan of e-Verify, as it just reinforces to me that the government has gotten itself in the business of licensing labor) but its a pretty interesting summary of just how muddled the Obama administration is on this topic. While I don't support our newest immigration law here in AZ, its easier to see why states like AZ feel the need to take some independent leadership on the topic.
In this brief, the Obama administration is challenging an earlier AZ state law that requires, as a condition to retain one's business license, that companies use e-Verify to check new employees legal work status (here and here). Unfortunately, Obama's head of Homeland Security (and thus all immigration-related activities) actually signed the law into being and the administration wrote a brief in favor of the law just 9 months ago, about the same time Congress reauthorized e-Verify without doing anything to strike down AZ implementation practices). I am not much of a legal scholar, but states use compliance with Federal programs all the time as minimum requirements for retaining business licenses -- e.g. non-payment of Federal taxes can cause one to lose his state business license, but no one has ever argued that is an illegal intrusion of states on federal powers. If the Feds want to argue all of these provisions are unconstitutional, fine by me. Anyway, the article linked above is highly entertaining.
Postscript: Here is the e-Verify post one must post in his business to be legally compliant:
This is fairly Orwellian for those of us who believe that all people have the right to work, irrespective of the country they were born in, and this right does not flow from any national government and therefore does not stop or start at any border.