One of the most remarkable things to come out of Washington this week had nothing to do with debt. It was about immigration. The Obama Administration on Monday filed a legal challenge to Alabama’s new immigration law, further animating the longstanding tension between federal supremacy and states’ rights. But it is especially noteworthy, given that Alabama is among the states, many of them Southern, that in recent months have enacted some of the nation’s most restrictive immigration policies.

Beginning on Sept. 1, Alabama will require local law enforcement authorities to check the citizenship status of people who appear to be illegal immigrants, a policy critics predict will open the door to racial and ethnic profiling lawsuits. It also will criminalize the act of providing transportation or housing to undocumented immigrants. Public school officials will be required to ask students to produce birth certificates to prove U.S. citizenship, or whether they are the child of illegal residents. Parents can be asked to sign a declaration of legal residency and schools must report those findings to Alabama’s board of education. The law’s chief architect, Micky Hammon, a Republican legislator, dismissed the Obama Administration’s suit on Monday, telling reporters: “They want to block our efforts to secure Alabama’s borders and prevent our jobs and taxpayers from disappearing into the abyss that illegal immigration causes.”

The Administration’s Alabama lawsuit comes weeks after it filed a legal challenge to Arizona’s new immigration policy. The federal actions matter for several key reasons. First, they are examples of how the Administration is using its prosecutorial discretion in the politically thorny matter of immigration policy. Especially given Congressional reluctance to modernize federal immigration law and deal with the country’s estimated 11 million undocumented immigrants. Beyond challenging Alabama and Arizona’s policies, the Administration is expanding deportation programs targeting illegal immigrants convicted of crimes in their home countries or the U.S. This has resulted in the deportation of some 1 million undocumented immigrants since President Obama took office – more than during his predecessor’s entire second term.

The Administration’s legal objection in Alabama is predicated on federal supremacy – that is, the Constitution empowers Congress to set laws that supercede all others. The suit argues that the Fourteenth Amendment makes clear the federal government has the exclusive authority to determine both who is a citizen, and to regulate the movement of foreign nationals within U.S. borders. It’s unclear whether the Alabama law’s education provision violates the U.S. Supreme Court’s 1982 Plyler v. Doe decision, which held that under the Fourteenth Amendment, undocumented immigrant children are entitled to a public education.

Alabama’s governor, Robert Bentley, a Republican, enthusiastically signed the new policy into law in June. Georgia and South Carolina have passed similar, albeit less restrictive, measures. But the issue of states’ rights is tricky, considering the terrain. The South’s support of states’ rights – particularly on slavery’s abolition – was a key cause of the Civil War. In the early 1960s, Alabama Governor George Wallace used the states’ rights argument to bar blacks from the state’s public schools – an action that ultimately moved President Kennedy to dispatch federal troops. “From a civil rights perspective, what states like Alabama are doing is going well beyond targeting undocumented immigrants,” says Cecilia Wang, director of the Immigrants’ Rights Project of the American Civil Liberties Union, which has joined several groups, including religious organizations, in challenging immigration policies in Alabama and other states. “In its anti-immigrant zeal,” Wang adds, “Alabama has really violated the civil rights of everyone in that state.”

The federal challenges to new laws in Alabama and Arizona don’t mean the Administration is dismissive of local immigration efforts. The federal government is actually recruiting local authorities to participate in some of its most aggressive deportation programs. Nevertheless, the federal action sends a clear message: States and local jurisdictions considering restrictive state immigration policies face cumbersome legal challenges.

Steven Gray is a Washington Correspondent at TIME. Find him on Twitter at @stevengray or at Facebook/gray.steven. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.