Principal investigator (PI)

PI status is conferred by award documentation rather than by career stage — an ECR can be a PI on a fellowship — but in practice the role implies institutional eligibility (typically requiring a continuing position). Co-PIs share responsibility; the lead PI is the formal contact and accountable party for compliance.

Principal Investigator Responsibilities

Eligibility determines who may hold the PI role; the responsibilities that come with it are what the role is actually accountable for. Across funders and institutions, PI accountability is generally described as non-delegable — an institution or sponsor can require named personnel and support staff to carry out specific tasks, but the PI remains the accountable party of record for the areas below.

Scientific and Technical Direction

The PI is responsible for the intellectual and technical direction of the funded work: designing the study, ensuring the methods described in the approved application or protocol are actually followed, and reporting results — both progress reports during the award and final reporting at closeout. Under the NIH Grants Policy Statement, the Program Director/PI is explicitly responsible for the scientific and technical conduct of the project, in addition to its fiscal aspects (see below); when a project has multiple PD/PIs, each one is individually responsible and accountable, and naming more than one PI does not dilute any individual’s accountability.

Financial Stewardship

Day-to-day fiscal stewardship — keeping spending aligned with the approved budget, justifying re-budgeting, and certifying that costs charged to the award are allowable, allocable, and reasonable — sits with the PI even though the recipient institution (through its Authorized Organizational Representative) holds the underlying legal and financial accountability to the funder. On federally funded research this includes certifying effort: confirming that the percentage of committed time charged to an award reflects work actually performed, a distinct compliance obligation covered in more detail in this site’s guide to effort-reporting methodologies.

Human Subjects and Animal Welfare Compliance

Where a project involves human participants or vertebrate animals, the PI is responsible for obtaining the required ethics approval before work begins, keeping that approval current through amendments and continuing review, and ensuring the study is actually conducted as approved. For human-subjects research this means working with the Institutional Review Board (IRB) (or the equivalent Research Ethics Committee outside the US); for animal research, the equivalent body is the Institutional Animal Care and Use Committee (IACUC). Deviating from an approved protocol, or continuing to enroll participants after approval has lapsed, is a compliance failure attributed to the PI regardless of who on the study team was directly involved.

Personnel Supervision

The PI supervises the study team — co-investigators, postdocs, research staff, and students working on the project — including making sure each person is qualified and, where relevant, credentialed or trained for the tasks they are assigned (human-subjects protections training, biosafety training, financial-conflict-of-interest disclosure, and similar institutional requirements). Supervision here means substantive oversight, not just nominal sign-off: funders and IRBs alike expect the PI to be able to demonstrate that delegated work was actually overseen.

Clinical Trials: FDA Form 1572 Investigator Obligations

In an FDA-regulated clinical trial conducted under an Investigational New Drug (IND) application, the principal investigator at each site signs FDA Form 1572 (Statement of Investigator), which is a formal commitment to the agency, not just to the sponsor. Under 21 CFR 312.60, by signing Form 1572 the investigator commits to personally conduct or supervise the described investigation; ensure that any staff to whom tasks are delegated are informed of their obligations; obtain informed consent from every subject before enrollment; report adverse events to the sponsor as required; maintain adequate and accurate study records; and ensure the study is conducted according to the investigational plan and applicable FDA regulations, including obtaining and maintaining IRB approval. These obligations sit alongside, rather than replace, the site’s own contractual terms with the sponsor, which are typically set out in a Clinical Trial Agreement (CTA).

References

• NIH Definition of Principal Investigator
• UKRI Eligibility for Principal Investigator Status
• NIH Grants Policy Statement, Section 2 (Recipient Staff / PD-PI responsibilities)
• 21 CFR 312.60 – Investigator responsibilities, general
• FDA Form 1572 (Statement of Investigator) and accompanying instructions