The query was raised by Justice Sadhana Jadhav while hearing a revision petition filed by CBI seeking permission to delete Chavan's name from the FIR in the case after Maharashtra governor K Sankaranarayanan refused to grant sanction to prosecute him.
The CBI had filed the petition in HC last month after the special CBI court refused to delete Chavan's name from the FIR filed in January 2011.
Chavan and 12 others were booked under section 120 (b) of the Indian Penal Code for criminal conspiracy and under various charges of corruption under the Prevention of Corruption (PC) Act.
"Do you (CBI) need sanction to prosecute under the general law of IPC," asked Justice Jadhav.
CBI lawyer Hiten Venegaonkar informed the court that sanction to prosecute under IPC was required as Chavan was a sitting MLA and former chief minister and also the revenue minister at the time when the alleged offence was committed.
"Without sanction under section 120 (b) of IPC, the agency cannot proceed to prosecute him under section 13 (1) (d) of the PC Act independently," he said.
HC has issued notices to the Maharashtra government and Chavan and kept the petition for hearing on June 10.
As Chavan was a chief minister, law required the state to give a prior sanction to prosecute him in a criminal case. Chavan had stepped down as CM after his name was linked to the Adarsh controversy towards the end of 2010.
CBI had accused Chavan of approving additional FSI (floor space index) to Adarsh society in exchange of two flats for his relatives. Chavan was also charged with illegally approving as revenue minister allotment of 40% of the flats to civilians when the society was allegedly meant for Kargil war widows and defence personnel.
Chavan had moved the high court against CBI's authority to probe the case.
CBI had filed a charge sheet in the case against 13 people, including 55-year-old Chavan, who is contesting upcoming Lok Sabha elections from Nanded, pending sanction from the governor. The trial court is yet to take cognisance of it.