Mandamus is an order for a government official to fulfill a legal duty that is not being performed. General Flynn filed one against Judge Sullivan to dismiss his case once the prosecutor declared he was dropping the charges. Sullivan, who is not a party to the case is illegally trying to force the prosecutor to keep prosecuting. It’s nuts.
Mandamus would force this corrupt DA to prosecute alleged violent crimes. Maybe it’s worth a try right?
Not worth a try, no. Mandamus orders, as applied to prosecutors or judges, are only useful (in practice, at least) for making them do ministerial tasks: drop these charges, return this property, etc. An order to prosecute a case to the best of your ability would result in a purposefully thrown case.