Colorado is trying again to block a lawsuit challenging the state's strict tax and spending limits.
The 10th Circuit of Appeals is scheduled to hear arguments in the case Monday morning.
Under the Taxpayers Bill of Rights, voters have the final say on any tax increases. Mostly Democratic current and former state lawmakers have filed a federal lawsuit challenging the state constitutional amendment, saying it violates the U.S. Constitution's requirement that all states have a republican form of government because it takes that power away from state and local elected officials.
A federal judge earlier rejected a motion from Attorney General John Suthers, on behalf of Gov. John Hickenlooper, to throw the case out.