Is there a point where nonlegal moral considerations supersede your ethical commitment to your client? If you were a defense lawyer and your client was innocent, but you could not prove it, would you violate ethical barriers in service to your client?

If you are an attorney, is there a point where nonlegal moral considerations supersede your ethical commitment to your client? If you were a defense lawyer and your client was innocent, but you could not prove it, would you violate ethical barriers in service to your client?