Clinical Investigations of Medical Devices

Clinical investigations of medical devices carried out in human subjects to assure the safety and performance of a medical device meet the manufactures intended claim. It is my understanding the device to be investigated can be a new medical device or a device already in the market. Do any one agree on this?.
A clinical investigation of medical device is considered as the back born with data to prove safe use of device. Results of the investigation moved to clinical evaluation report to demonstrate safety and performance. ISO 14155:2011 addresses good clinical practice to perform Clinical Investigations of Medical Devices.
Any one can detail the requirement of ISO 14155:2011 compliance to Medical Device Clinical Evaluation for above 2 conditions.