On several counts Karunanidhi can be challened in court.
1) Practising bigamy : Hwe is legally wedded to Dayalu Ammal and has three sons . Alagiri , Stalin and one more . The other women is Rajathi Ammal - Kanimozhi his daughetr is through her. Both are alive ( His first wife died long ago and he has one son MK Muthu)
2) He has called Hindus theifs on many occasions and recent blatant attack on Hindu community and it's beleifs.
Both above are against constitution and illegal.
If some good lawyer challenges him he can be dislodged from his MLA seat. Request Pls. contact me . I can bear all the costs of litigation. It has to be done in supreme court