Andi Mukta Sadguru Shree Muktajee Vandas Swami Suvarna Jayanti Mahotsav Smarak Trust v. V.R. Rudani, (1989) 2 SCC 691

The duty must be judged in the light of positive obligation owed by the person or authority to the affected party. No matter by what means the duty is imposed, if a positive obligation exists, mandamus cannot be denied.