In England that law already exists. It's called the Coroners and Justice Act. http://www.legislation.gov.uk/ukpga/2009/25/contents
You want to read about the reforms which arose out of the Shipman and Mid Staffs scandals (the Shipman Inquiry and the Francis Inquiry). You can read about those here: https://www.gov.uk/government/publications/changes-to-the-de...