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Informed consent means that a person agrees to take part in research only after receiving the information a reasonable person would want, in language they can understand, with the freedom to say no or withdraw. In US federally regulated research it is both an ethical principle and a documented regulatory requirement. This guide is general information for researchers and research staff, not legal or medical advice.
Short answer: what informed consent means
Under the HHS Common Rule, 45 CFR 46.116(a), investigators must obtain the legally effective informed consent of the subject or the subject’s legally authorized representative before involving the person in research. The consent process must give enough information that a reasonable person would want to have in order to decide, allow an opportunity to discuss it, take place under circumstances that minimise the possibility of coercion or undue influence, and use language understandable to the subject.
Definition and scope
Informed consent is a process, not only a signature. The regulation text asks for a setting with sufficient opportunity to consider participation, understandable language, and a presentation organised to help comprehension. Consent must also begin with a concise and focused presentation of the key information most likely to help a prospective subject understand why they might or might not want to participate. The text may not include exculpatory language through which the subject appears to waive legal rights or release the investigator, sponsor or institution from negligence (see exculpatory language in informed consent).
In the US, two regulations set the required content: 45 CFR 46 (HHS, applies to human subjects research conducted or supported by HHS and to institutions that extend it) and 21 CFR 50 (FDA, applies to clinical investigations regulated by FDA). Their differences are summarised in 45 CFR 46 vs 21 CFR 50 and the wider framework in 45 CFR 46 subparts explained.
Why is informed consent important?
The purpose of informed consent is to let a prospective participant decide, on their own terms, whether the research fits their interests and values. Its ethical basis in US research is respect for persons, one of the three principles of the Belmont Report (see Belmont Report principles). In practice it also gives a recorded basis for showing that participation was voluntary and informed.
How informed consent is used in practice: required elements
Both regulations list basic elements every consent must contain, and additional elements added when appropriate to the study. The table below is a side-by-side crosswalk of the text of 45 CFR 46.116(b)-(c) and 21 CFR 50.25(a)-(b), read 2026-11-07.
| Element | 45 CFR 46.116 (HHS) | 21 CFR 50.25 (FDA) |
|---|---|---|
| Research statement: purposes, duration, procedures, which are experimental | Basic (b)(1) | Basic (a) |
| Foreseeable risks or discomforts | Basic (b)(2) | Basic |
| Benefits | Basic (b)(3) | Basic |
| Alternative procedures or treatment | Basic (b)(4) | Basic |
| Confidentiality of records | Basic (b)(5) | Basic; also must state that FDA may inspect the records |
| Compensation or treatment for injury (research of more than minimal risk) | Basic (b)(6) | Basic |
| Contacts for questions, research-subject rights and research-related injury | Basic (b)(7) | Basic |
| Participation is voluntary; no penalty or loss of benefits for refusing or withdrawing | Basic (b)(8) | Basic |
| Future use of identifiable private information or biospecimens (identifiers removed and reused, or not used for future research) | Basic (b)(9) | No equivalent element |
| Unforeseeable risks, including to an embryo or fetus | Additional (c) | Additional (b) |
| Investigator may end participation without the subject’s consent | Additional (c) | Additional (b) |
| Additional costs to the subject | Additional (c) | Additional (b) |
| Consequences of withdrawal | Additional (c) | Additional (b) |
| Significant new findings shared with the subject | Additional (c) | Additional (b) |
| Approximate number of subjects | Additional (c) | Additional (b) |
| Possible commercial profit from biospecimens; disclosure of clinically relevant results; whole genome or exome sequencing | Additional (c) (three further elements) | No equivalent element |
| ClinicalTrials.gov statement (“A description of this clinical trial will be available on http://www.ClinicalTrials.gov, as required by U.S. Law.”) | Not in this section | Required for applicable clinical trials, 50.25(c) |
What the crosswalk shows: HHS has nine basic and nine additional elements; FDA has eight basic and six additional. The FDA-inspection statement and the ClinicalTrials.gov statement exist only on the FDA side; the future-use statement, the three extra additional elements and broad consent exist only on the HHS side. A study that falls under both regimes needs a form that satisfies both. For a checklist-style walk-through of the HHS elements see the informed consent checklist for researchers.
What is an informed consent form?
An informed consent form is the written document that presents the required information and, where documentation is required, records the subject’s agreement. The form supports the consent process; it does not replace the discussion. Where an IRB waives documentation of consent, the information must still be provided (see waiver of informed consent).
Broad consent
45 CFR 46.116(d) allows an alternative, broad consent, for the storage, maintenance and secondary research use of identifiable private information or identifiable biospecimens. It carries a subset of the basic elements plus a description of the types of research that may be conducted. It is an HHS option with no counterpart in 21 CFR 50.25. See broad consent under 45 CFR 46.116(d).
What happens if you do not get informed consent?
Consent cannot simply be skipped. Under 45 CFR 46.116(f), an IRB may approve a consent procedure that omits or alters some or all elements, or waive the requirement entirely, only if it finds and documents that the research involves no more than minimal risk, could not practicably be carried out without the waiver or alteration, (if it uses identifiable information or biospecimens) could not practicably be carried out with non-identifiable data, will not adversely affect the rights and welfare of subjects, and, where appropriate, subjects will be given pertinent information afterward. The general requirements of 46.116(a) cannot be altered through this route. Research conducted without consent and without such a determination is a compliance problem for the institution’s IRB and research office to handle; consequences depend on the sponsor, institution and regulator, and this guide does not predict them.
Common misunderstandings
- “Consent is the signed form.” The rule describes an exchange of information with an opportunity to discuss; the form documents it.
- “A long form is a better form.” The regulation requires a concise key-information opening and organisation that aids understanding, not exhaustive length.
- “Subjects can waive their rights in the form.” Exculpatory language is prohibited.
- “HHS and FDA lists are identical.” They differ, as the crosswalk shows.
- “Consent and HIPAA authorization are the same.” They are separate permissions; see HIPAA authorization vs informed consent. For minors, see informed consent vs assent.
Where it matters for labs and clinics
Any lab or clinic team that enrols human participants, or uses identifiable biospecimens or data, needs consent language reviewed by an IRB against the correct regulation. The first step is working out which regime applies (HHS, FDA or both). The CASRAI dictionary entry for informed consent gives the short definition.
Frequently asked questions
What is informed consent in health care?
This guide covers research consent under 45 CFR 46 and 21 CFR 50. Consent to routine clinical treatment is governed separately by state law and institutional policy, and is not described here.
Why is consent important?
It puts the participant, not the investigator, in charge of whether to take part, with the information a reasonable person would want.
What do you mean by informed consent form?
The document presenting the required elements and recording agreement; see the section above.
What does informed consent mean in research?
Legally effective agreement obtained before participation, containing the required elements, free from coercion or undue influence, and revocable without penalty.
Sources
- 45 CFR 46.116, General requirements for informed consent (Cornell LII copy of the eCFR text), read 2026-11-07: law.cornell.edu/cfr/text/45/46.116
- 21 CFR 50.25, Elements of informed consent (Cornell LII copy), read 2026-11-07: law.cornell.edu/cfr/text/21/50.25
