Today, Attorney General Holder and the Obama DOJ will file suit against Arizona’s "show me your papers" law:

The Obama administration will argue that S.B. 1070, the state’s controversial immigration law, set to take effect later this month, is unconstitutional.

President Obama, Attorney General Eric Holder, and Secretary of State Hillary Clinton have publicly criticized the law, which would give police officers the authority to question people they suspect are illegal immigrants.

Civil rights groups say the law could lead to widespread racial profiling, but Arizona says it is giving law enforcement officers training on how to avoid potential pitfalls.

Jerry Markon, of The Washington Post, outlines the government’s legal argument:

The lawsuit … will invoke for its main argument the legal doctrine of "preemption," which is based on the Constitution’s supremacy clause and says that federal law trumps state statutes.

Clearly, this is progress. I’m no Constitutional scholar, but the administration’s legal case appears to me to be strong. However, legal cases like this are no sure thing.

The Arizona law, SB1070, goes into effect on July 29th. Will the administration ask for and get an injuction while the legal case proceeds? And if this case gets to the Supreme Court, will they overturn the law? I’m personally hesitant to bank on the Supreme Court doing anything progressive, given its current makeup.

So while this immensely important suit goes forward, there’s more that needs to be done. There are over 425,000 unregistered Latinos and Africa-Americans in Arizona. A group I’m working with, Promise Arizona, has started a campaign to register them to vote and turn them out in November. Other groups in Arizona are working towards this goal as well.

Given that Republican Governor Jan Brewer, who signed the law, is being challenged by Democrat and current AZ attorney general Terry Goddard and Goddard is leading in polls [pdf] that aren’t non-trustworthy Rasmussen polls, these voters could very well make the difference and put someone in office who’s against the law, is refusing to help defend it as AG, and believes in comprehensive immigration reform.