“We are not talking here about a federal law prohibiting the States from regulating bubble-gum advertising, or even the construction of nuclear plants. We are talking about a federal law going to the core of state sovereignty: the power to exclude. […] The Court opinion’s looming specter of inutterable horror—‘[i]f [Section] 3 of the Arizona statute were valid, every State could give itself independent authority to prosecute federal registration violations’—seems to me not so horrible and even less looming. But there has come to pass, and is with us today, the specter that Arizona and the States that support it predicted: A Federal Government that does not want to enforce the immigration laws as written, and leaves the States’ borders unprotected against immigrants whom those laws would exclude. So the issue is a stark one. Are the sovereign States at the mercy of the Federal Executive’s refusal to enforce the Nation’s immigration laws? […] Arizona bears the brunt of the country’s illegal immigration problem. Its citizens feel themselves under siege by large numbers of illegal immigrants who invade their property, strain their social services, and even place their lives in jeopardy. Federal officials have been unable to remedy the problem, and indeed have recently shown that they are unwilling to do so. […] Arizona has moved to protect its sovereignty—not in contradiction of federal law, but in complete compliance with it. The laws under challenge here do not extend or revise federal immigration restrictions, but merely enforce those restrictions more effectively. If securing its territory in this fashion is not within the power of Arizona, we should cease referring to it as a sovereign State.”

Concurring in part and dissenting in part, Arizona v. United States (2012) : 567 U.S. ___ (2012); decided June 25, 2012.
2010s