That's the ruling Thursday from Attorney General Lisa Madigan.
Madigan says the state does not have authority to take a $200 million loan against the Thompson Center.
That deals another blow to the budget plans of Gov. Rod Blagojevich. The mortgage was supposed to help erase the state's massive deficit.
But Madigan says the mortgage would be new state debt, which must be approved by a three-fifths vote of the Legislature. The bill to approve the plan passed by a simple majority in the state Senate.
Madigan issued the opinion at the request of Senator Peter Roskam, a Wheaton Republican. He says Blagojevich should abandon the mortgage plan and cut spending to make up for it.