How many Presidents have joined other countries in suing states?? [Reader Post]

Barack Obama has already sued the state of Arizona.

Claiming “preeminent authority” to write the laws on immigration, the Justice Department filed suit to block Arizona from enacting its own.

“Setting immigration policy and enforcing immigration laws is a national responsibility,” said Attorney General Eric Holder. “Seeking to address the issue through a patchwork of state laws will only create more problems than it solves.”