What Is an IRB? A Complete Definitional Guide

An Institutional Review Board (IRB) is an independent committee that reviews, approves, and monitors research involving human subjects to ensure participant safety and ethical compliance. IRBs operate under federal regulations established by the Food and Drug Administration (FDA) and the U.S. Department of Health and Human Services (DHHS) to protect the rights and welfare of all research participants. 

If you are involved in clinical research — whether as a sponsor, investigator, or compliance leader — understanding what an IRB is, what it does, and why it matters is foundational to conducting ethical, audit-ready studies. 

IRB Meaning: Breaking Down the Definition 

The term IRB stands for Institutional Review Board. In international research settings, the equivalent body is referred to as an Independent Ethics Committee (IEC), as defined in the ICH E6 Good Clinical Practice (GCP) guidelines. In Canada, the equivalent body is referred to as Research Ethics Boards (REBs). All of these terms describe the same essential function: independent, ethical oversight of research involving human participants. 

In the United States, IRBs are governed by two primary regulatory frameworks: 

• 21 CFR Parts 50 and 56 — FDA regulations covering research on drugs, biologics, and medical devices. 

• 45 CFR Part 46 — the “Common Rule,” which governs federally funded human subjects research. 

Any research that is either federally funded or subject to FDA oversight requires review and approval from a properly constituted IRB before it may proceed. 

Key Functions of an IRB 

An IRB performs several distinct and critical functions throughout the lifecycle of a clinical study. These are the core responsibilities that define how an IRB operates: 

• Protocol Review: Evaluates the scientific and ethical design of a research protocol prior to study initiation, assessing risks to participants relative to anticipated benefits. 

• Informed Consent Oversight: Reviews and approves the informed consent process and materials to ensure participants receive complete, comprehensible information before agreeing to participate. 

• Risk-Benefit Assessment: Determines whether the risks to participants are minimized and reasonable in relation to the expected benefits of the research. 

• Approval, Modification, or Disapproval: Has the authority to approve a study as submitted, require modifications before approval, or disapprove research that does not meet ethical and regulatory standards. 

• Continuing Review: Monitors approved research at intervals appropriate to the degree of risk to ensure ongoing compliance and participant safety. 

• Adverse Event Review: Evaluates unanticipated problems, serious adverse events, and protocol deviations to determine whether changes are needed to protect participants. 

• Regulatory Compliance Verification: Confirms that research activities comply with applicable federal regulations, Good Clinical Practice (GCP) standards, and, when applicable and known, institutional policies. 

• Vulnerable Population Protections: Applies additional safeguards when research involves children, pregnant women, prisoners, or individuals with impaired decision-making capacity. 

Types of IRB Review 

Not all research undergoes the same level of scrutiny. The regulations identify three distinct categories of IRB review:

Full Board Review 

Required for research that presents greater than minimal risk to participants. The full IRB committee convenes to evaluate the protocol, and a majority vote is required for approval. This is the most comprehensive form of review and typically applies to clinical trials. 

Expedited Review 

Applicable to research that poses no more than minimal risk and fits within one of the specific categories defined in federal regulations. A single IRB reviewer or a small subgroup conducts the review, allowing for faster turnaround without sacrificing rigor. 

Exempt Review 

Applies to certain low-risk research categories that qualify for exemption under 45 CFR 46. While exempt studies do not require IRB review, a determination of exempt status must still be made by the IRB or a designated reviewer — not by the researcher alone. While researchers can indicate that they believe their study may qualify for exempt status, other bodies, like institutional offices, can legally make the final determination. Self-certification is not permitted under federal regulations. 

Membership and Structure 

Federal regulations specify the minimum composition of an IRB to ensure diverse, balanced oversight. A properly constituted IRB must include: 

• At least five members with varying backgrounds. 

• At least one member whose primary concerns are in scientific areas. 

• At least one member whose primary concerns are in nonscientific areas. 

• At least one member who is not otherwise affiliated with the institution. 

• Members with sufficient expertise to review the specific research under consideration. 

In practice, experienced IRBs — particularly central or independent IRBs — draw on much larger, more diverse boards. Understanding the distinction between an institutional IRB and a central IRB is important for multi-site research sponsors and compliance leaders. 

Why IRB Review Matters for Regulatory Compliance 

For regulatory and compliance leaders, IRB oversight is not a procedural checkbox — it is a critical control in the broader framework of regulatory compliance, data integrity, and audit readiness. An IRB determination is: 

• Required before study initiation under FDA regulations (21 CFR Part 56). 

• A prerequisite for IND and IDE submissions to the FDA. 

• An element evaluated during FDA and sponsor audits. 

• Central to protecting participant welfare and the ethical validity of data. 

Failure to secure or maintain valid IRB approval can result in clinical holds, audit findings, and potentially invalidated study data. Partnering with a credentialed, experienced IRB is one of the most consequential decisions a compliance team makes. 

IRB in Research: A Brief History 

The modern IRB system traces its origins to a series of historical events that exposed serious ethical failures in research conduct. The Nuremberg Code (1947) and the Declaration of Helsinki (1964) established early international principles for ethical research. In the United States, the Belmont Report (1979) — produced by the National Commission for the Protection of Human Subjects — laid the ethical foundation for current federal regulations by articulating three core principles: 

1. Respect for Persons: honoring individual autonomy and informed consent. 

2. Beneficence: maximizing benefits and minimizing harms. 

3. Justice: ensuring equitable distribution of research burdens and benefits. 

These principles continue to guide IRB review today and are embedded in the regulatory frameworks administered by the FDA and OHRP. 

Frequently Asked Questions About IRBs 

What is the difference between an IRB and an IEC? 

An IRB is the term used in the United States, regulated under FDA and DHHS guidelines. An IEC is the equivalent body used in international research settings and referenced in ICH E6 GCP guidelines. Both serve the same fundamental purpose; protecting human research participants. 

How long does IRB review take? 

IRB review timelines vary depending on the complexity of the study and the type of review required. Full board reviews are conducted at convened meetings, while expedited reviews can be completed more quickly.  

What is AAHRPP accreditation, and why does it matter? 

The Association for the Accreditation of Human Research Protection Programs (AAHRPP) is the gold standard for demonstrating that an IRB meets rigorous standards for human research protection. AAHRPP accreditation provides sponsors, investigators, and regulators with independent verification that an IRB’s processes are thorough, ethical, and compliant.