A Patiala House court in Delhi has asked Janata Party President Subramanian Swamy to present his case on January 21, on why Home Minister P Chidambaram should be summoned and made a co-accused in the 2G case. "On January 21, I will argue on why Chidambaram should be summoned. I will explain how he was involved in this scam and should therefore be made an accused based on my evidence," said Mr Swamy.