emogration?
For one it is not legal for Obama to give theses aliens green cards simply for him to fail to deport them. (Which to be frank is what he has been doing for the past 3 years anyway unofficially).
Simply being a bad president and sleeping on the job(or constant vacationing in his case) is not in itself a usurpation. A usurpation consist only in actions which violate rights not ceded to the same government in its Constitution. (IE: Unauthorized acts of the federal Government in this case)
States act similarly. They can enforce Federal acts if they consent to them, or they can simply stand back and do their own thing leaving Washington to enforce its own rules.(largely leaving the same unenforced when it comes to domestic matters)
Their refusal or “neglect” to help Washington do its own job is not in itself illegal nor is it particularly uncommon. Their independent acts in areas forbidden to them however is illegal.
In other-words a State can arrest & jail illegal aliens(largely the only realistic way its going to get done) but not if Washington changes the Law to make them legal. Obama as president similarly can neglect to aggressively go after illegal aliens, but he can’t go after Ohioan Joe the plummer because there is no law that makes Ohioan Joe’s present and work in his own state of Ohio illegal.