The fight over the film title Leader has gone before a court in Bengaluru. But if you look at judgement by the high courts and even the Supreme Court over the last few years it is clear that you cannot have a copyright on the title of any work, including films, books and music albums. There is copyright on the work itself but not on the titles.
The most famous case was two years ago when a writer challenged the use of the Hindi film title Desi Boyz. He claimed that it was infringing on his copyright as he had written a script called Desi Boys and shown it to the film maker. But the Supreme Court ruled (CRIMINAL APPEAL No. 258 OF 2013) that "A title does not qualify for being described as work". Further the court said that the words Desi and Boys were commonly used in spoken language and there cannot be copyright on it. So will there be copyright on words 'Mass' or 'Leader'. It cannot be.
There was another case involving Tamil director A.R. Murugadoss. In this case the Madras High Court ruled that there cannot be any copyright on the words like Raja and Rani. The film's title was Raja Rani.
The only case that can stand scrutiny is if one title is passing off as another. If the makers of Mass Leader are trying to sell their film as if it is the film Leader then it can be a case. But here it is Shivarajkumar starrer Mass Leader that is complete and it cannot be passed off as a film that is not even made.
Also See
Mass Leader Censored; Releasing On August 11th
The Leader Shivarajkumar Now as Mass Leader
No Copyright on Film Titles Says Supreme Court - Exclusive
Court Stay On Mysore Mallige Title - Exclusive
Why are so Many Film Titles in Controversy? - Exclusive
