Mr N.K. Assumi,
I am a doctor. With respect to this case, the husband should check if the patient's severe mental illness was hidden from him by his inlaws, including his wife, if she suffered any such severe mental illness prior to her marriage, in which case the mental health law 1987 says that it is against law. But if the ilness is after marriage then the husband will have no grounds but it will be his responsibility to get her treated atleast by a reception order from the magistrate for involuntary admission to a recognised psychiatric hospital if she refuses treatment and for this the husband must get in touch with a psychiatric doctor ie the psychiatrist.