Karunanidhi was arrested on March 28 after he stopped a police sub-inspector from entering the Intensive Care Unit (ICU) of Apollo Hospital with his shoes on. He is currently out on bail.
According to the government, the policeman had gone to the Apollo Hospital ahead of Chief Minister J Jayalalithaa's visit to meet media baron Sivanthi Adithan, admitted to the hospital. Dr Karunanidhi is the personal physician of Adithan.
Karunanidhi has been charged with assault and preventing the government official from discharging duty.
A section of doctors in Chennai have announced a protest on April 6 over the arrest of the doctor. The doctors on protest want withdrawal of case against Dr Karunanidhi, a retired government doctor.
Meanwhile, DMK chief M Karunanidhi condemned the move and demanded "action against those responsible" and "unconditional withdrawal of charges" against the doctor.