David Rivkin Jr. and Lee Casey argued for months that the health-care overhaul under consideration in Congress was unconstitutional. Now, the two Baker Hostetler partners will have a chance to make the case in court.

Rivkin and Casey, who work in the firm’s Washington office, have signed on as outside counsel to several state attorneys general who want the legislation overturned in court. The litigation is the initial wave of what is expected to be a long series of lawsuits challenging various pieces of the overhaul, which won final congressional approval March 21.

“We’re talking about constitutional dialogue at the highest level,” Rivkin said.

A lawsuit is expected to be filed in federal court as soon as President Barack Obama signs the legislation March 23. Rivkin said Florida will be the lead plaintiff, with Baker Hostetler serving as outside counsel to the state’s attorney general, Bill McCollum, and to any other state attorneys general that sign on to the lawsuit. About 12, including those from South Carolina and Utah, are expected to do so.

Rivkin, in an interview March 22, said a venue had not been decided but that the Northern District of Florida is likely. The district includes Florida’s capital, Tallahassee.

Virginia Attorney General Ken Cuccinelli, also a Republican, is expected to file a separate federal lawsuit March 23 in the Eastern District of Virginia. The state is in a different position than the others because lawmakers there passed a law banning government-required health insurance. A spokesman said Cuccinelli’s office will represent the state without outside counsel.

Florida’s lawsuit will make three claims, Rivkin said: that Congress lacks the authority to require individuals to buy health insurance; that the penalty for those who do not buy health insurance violates the U.S. Constitution’s tax-apportionment clause; and that the legislation violates the 10th Amendment by granting the federal government new powers.

Democratic commentators and liberal lawyers have defended the legislation’s constitutionality by citing the wide latitude generally granted Congress to regulate interstate commerce and to impose taxes.

Casey and Rivkin served in various capacities in the Reagan and George H.W. Bush administrations, and they’ve been frequent commentators on the constitutionality of Democrats’ health-care proposals. Rivkin said it’s “enormously gratifying and intellectually rewarding” to work on the case, even though he wishes the legislation were not becoming law. Baker Hostetler is taking on the case at a “substantially reduced” rate, he said.

Among the issues likely to come up in the lawsuit is whether states have standing, given that the requirement to purchase insurance affects individuals, not states, most directly. “I don’t think states are well-positioned to argue the unconstitutionality of the individual mandate,” said Georgetown University law professor Randy Barnett. A conservative, Barnett said he’s “open” to working on a similar lawsuit on behalf of individuals.

Rivkin said the states nonetheless have an interest, especially in bringing a challenge under the 10th Amendment, because state resources and personnel could be used to implement the law.

David Ingram can be contacted at dingram@alm.com.