Republican lawmakers and anti-tax groups are suing to block an $18 billion Democratic budget package.
They claim it included tax increases that were not passed by the required two-thirds majority in the Legislature.
The budget bill, intended to close a widening state deficit, was passed last month by the Democratic-majority Legislature but has not yet been sent to the governor.
The suit alleges that the bill violated state and federal laws because it swapped taxes for what Democrats referred to as fees on a simple majority vote.
Supporters of the lawsuit say the Legislature's action amounted to taking private property without due process.