it would be most surprising if state and local officers lacked the authority, where appropriate, to arrest individuals suspected of committing federal crimes such as bank robbery, kidnapping or terrorism. State and local officers are not required to stand idly by and allow such criminals to proceed with impunity. The same holds true with criminal violations of the immigration laws.One slight problem with that analysis--unlawful presence in the United States is a civil, not criminal, offense. See 8 U.S.C. §§ 1182(a)(6)(A)(i), 1227(a) (1)(B)-(C). (For additional support and a more detailed legal analysis, see this very helpful CRS Report from March 2009.) That distinction is critical to understanding the current legal battle involving SB1070. It has long been understood that state law enforcement officers may enforce federal criminal laws, but they may not enforce not federal civil laws unless there is an express delegation of authority.
There have been several efforts in Congress to criminalize unlawful presence (which are summarized in this CRS Report from 2006), but they have all failed. There has also been some effort to provide states with express authority to enforce civil violations of immigration law, but they too have been unsuccessful.
In the complaint the United States filed against SB1070, the government argued that Arizona's law effectively criminalizes the unlawful presence of aliens "despite an affirmative choice by Congress not to criminalize unlawful presence" (see paragraph 54). In its preliminary ruling blocking enforcement of aspects of that law, the district court agreed and held that SB1070 creates new criminal penalties that are in direct conflict with the pervasive scheme established by Congress. It therefore enjoined Arizona from enforcing certain provisions for now, until the court has had the opportunity to reach a final decision on the merits.
Virginia's AG Cuccinelli completely brushes aside the distinction between civil and criminal violations. Instead, in the opinion letter he attempts distinguish between the authority of a state law enforcement officer to arrest an individual who is unlawfully in the United States, and the authority to detain and interrogate someone who the officer reasonably suspects may have violated the law. That distinction is poppycock. The point is and has always been that civil enforcement of federal laws is left to the feds, unless the feds expressly authorize the states to get involved. Through this opinion letter, Cuccinelli usurps authority that clearly belongs to the federal government by effectively declaring that unlawful presence is criminally sanctionable in Virginia.