An IRB, or institutional review board, is a committee that reviews research involving people to make sure participants are treated ethically and safely. Any study that enrolls human subjects at a U.S. institution receiving federal funding must be reviewed by an IRB before it can begin. The board has the authority to approve a study, require changes, or reject it entirely.
What an IRB Actually Does
An IRB’s core job is to evaluate a research plan before anyone is enrolled, then monitor the study as it progresses. The board reads through the full research protocol, the informed consent documents that participants will sign, and any materials describing potential risks. Its goal is to confirm that the study is designed to protect participants’ rights and wellbeing.
The term “IRB” is a generic label used by both the FDA and the Department of Health and Human Services. It doesn’t refer to one specific organization. Universities, hospitals, and research institutions each maintain their own IRBs, and independent IRBs also exist to serve smaller organizations that don’t have their own boards.
The Ethical Principles Behind IRB Review
IRBs operate on three principles laid out in the 1979 Belmont Report, a foundational document in research ethics.
- Respect for persons. Participants must be given enough information to make a genuine, voluntary choice about joining a study. No one should be pressured or coerced. People with limited ability to make decisions for themselves, such as young children or individuals with cognitive impairments, deserve extra protection.
- Beneficence. The study should minimize harm and maximize potential benefit. Risks to participants must be justified by what the research stands to gain for the individual or for society.
- Justice. The burdens and benefits of research should be distributed fairly. Researchers can’t target vulnerable groups simply because they’re easy to recruit.
What the Board Checks Before Approving a Study
Federal regulations spell out specific criteria an IRB must verify. The board confirms that the research design doesn’t expose participants to unnecessary risk, and that any remaining risks are reasonable compared to the expected benefits. It checks that participants are selected fairly, with special attention to groups vulnerable to coercion: children, prisoners, people with impaired decision-making, and economically or educationally disadvantaged populations. When a study involves these groups, the IRB requires additional safeguards.
The board also confirms that every participant will go through a proper informed consent process, that there are plans to monitor safety data during the study, and that the researchers have adequate provisions to protect participants’ privacy and keep their data confidential.
Who Sits on an IRB
An IRB must have at least five members with diverse backgrounds. Federal rules require at least one member whose expertise is in a scientific field and at least one whose expertise is in a nonscientific area. At least one member must have no affiliation with the institution running the board, providing an outside perspective. The regulations also call for diversity in race, gender, and cultural background so the board can meaningfully evaluate how a study might affect different communities.
If a board regularly reviews research involving vulnerable populations, it should include members with direct experience working with those groups.
Three Levels of Review
Not every study goes through the same review process. The level depends on how much risk participants face.
Exempt review applies to research that poses very little risk, such as anonymous surveys, educational tests, or observation of public behavior. These studies still get evaluated, but through a streamlined process. Some exempt studies undergo what’s called a “limited IRB review,” which is a narrower check focused on specific protections like privacy rather than the full set of approval criteria.
Expedited review is used when a study involves no more than minimal risk, meaning the likelihood of harm is no greater than what someone would encounter in daily life or during a routine medical exam. One or two experienced IRB members can conduct this review rather than convening the entire board. Expedited review also covers minor changes to studies that have already been approved.
Full board review is required for any study that doesn’t qualify for exemption or expedited review. This means the complete IRB meets, discusses the protocol, and votes. Studies involving greater-than-minimal risk, experimental treatments, or vulnerable populations typically go through this process.
Ongoing Oversight After Approval
Approval isn’t a one-time event. An IRB must conduct continuing review at least once a year, and more frequently if the study carries higher risks. The board considers factors like how vulnerable the participants are, whether the study involves novel interventions, and the researchers’ track record when deciding how often to check in.
During these reviews, researchers submit progress reports that include any unanticipated problems or adverse events that have occurred since the last review. If unexpected safety concerns emerge, that information directly affects whether the board decides the study’s risk-benefit balance still holds up. The IRB can require changes to the study or withdraw its approval at any point.
The Federal Rules That Govern IRBs
Two main sets of federal regulations apply to IRBs. The first is 45 CFR 46, commonly known as the Common Rule, which is enforced by the Office for Human Research Protections within the Department of Health and Human Services. This rule covers all federally funded research involving human subjects and has been adopted by most federal agencies.
The second is a set of FDA regulations that governs clinical trials for drugs, devices, and biological products regardless of funding source. While the two frameworks overlap significantly, they diverge on some details. For example, the revised Common Rule eliminated the requirement for annual continuing review of minimal-risk studies eligible for expedited review, but the FDA chose not to adopt that change, maintaining that yearly reviews of even low-risk clinical investigations provide meaningful protection. The FDA also has its own rules around consent documentation and uses a slightly different definition of identifiable private information that includes whether a study sponsor (not just the researcher) could identify a participant.
Single IRB Requirements for Multi-Site Studies
Research conducted at multiple locations across the U.S. used to require separate IRB approval at every site, creating redundant reviews and delays. Since January 2020, the revised Common Rule requires that multi-site studies involving non-exempt human subjects use a single IRB. The NIH had already begun phasing in this requirement for its funded research starting in 2018.
Under this system, one IRB serves as the reviewing authority for all domestic sites in a study. Individual sites can still refuse to participate based on local considerations, but the ethical review itself is centralized. This change was designed to speed up the approval process for large collaborative studies while maintaining consistent oversight.