My sister quarreled with her brother-in-law, and as a result, my sister drank medicine herself and died. My sister's parents are suing my brother-in-law. Is it possible to win the case?

I advise you to tell her parents to give up the idea at once. Winning the case is impossible. If your sister decided to commit suicide and your brother-in-law was not there, it would have to be abandoned. Prosecution is just a waste of money and energy. I have experienced such a thing once, and I can only admit that I am unlucky and can't find any reason to win. .