2 CFR 1108.295: Principal investigator.

Principal investigator means either:

(a) The single individual whom an organization that is carrying out a research project with DoD support designates as having an appropriate level of authority and responsibility for leading and directing the research intellectually and logistically, which includes the proper conduct of the research, the appropriate use of funds, and compliance with administrative requirements such as the submission of performance reports to DoD; or

(b) If the organization designates more than one individual as sharing that authority and responsibility, the individual within that group identified by the organization as the one with whom the DoD Component's program manager generally should communicate as the primary contact for scientific, technical, and related budgetary matters concerning the project (others within the group are “co-principal investigators,” as defined in this subpart).