Typically the Quality Manager is responsible for the entire Quality Management System and all QC personnel, as well as compliance to requirements from customers, regulating bodies, etc. As for the actual "authority" of the Quality Manager, that should be determined by company management, and should be noted in a formal job description. The Quality Manager should have the authority to reject and quarantine product, shut down production processes when necessary, implement containment actions, require inputs from other departments and disciplines, etc. Unfortunately as anyone in "quality" knows, all sorts of things can get assigned to the quality department that really should not be. Most times the Quality Manager reports to the Plant Manager, which in my view can result in a conflict of interest at times (been there...done that).