What primary responsibility does the Principal Investigator (PI) hold at each participating site?

Overseeing every aspect of the study conduct at their location.

The Principal Investigator (PI) serves as the authorized healthcare professional appointed at every location where the clinical trial is being conducted, making them the central figure for site-level operations. Their responsibility is comprehensive, covering oversight of every single element of the study taking place at their specific site. This oversight begins at the conceptual phase, extending through the rigorous process of writing the detailed protocol description. Furthermore, the PI is responsible for obtaining mandatory approval from the Institutional Review Board (IRB) before proceeding. They also supervise all site staff involved in the trial execution. Critically, the PI carries the ultimate burden for ensuring all study procedures are followed correctly, which includes the fundamental ethical obligation of confirming that every participant fully understands their rights and explicitly consents to participation.