The appointment was a bid to break a leadership deadlock in the state Senate.
The move appeared to succeed. Rebel Democratic Sen. Pedro Espada dropped a month-long affiliation with Senate Republicans and returned to his party.
That ended a month-long stalemate in the statehouse. But it set off the court fight over Ravitch's appointment.
A Senate attorney contends the appointment of Ravitch is unconstitutional. Paterson's lawyer says the governor is within his rights.