I recently watched Dangal (Indian Movie about wrestling) and in that movie, coach "Pramod Kadam" (Character name: "coach from NSA/NIS") was characterised as a negative role. Later I heard that "PR Sondhi" (Assumed real name of character "Pramod Kadam") was upset about how he was characterised in that movie.
So before doing a movie like Dangal, M.S. Dhoni: The Untold Story or Sachin: A Billion Dreams, do the film makers contact all main characters and get a signed consent after showing the screenplay (at least their part in the movie?).
Is there any rule to get signed consent from all real life characters while doing biography movies? (If possible I want specific answer about Indian movies).
If there is any such rule, was PR Sondhi not properly informed about the character to increase the dramatic content in the movie?
If there is no such rule, can this be exploited just like the above example for the reach of the movie?