Informed Consent in Clinical Trials: The Regulatory Guide for CRCs

Informed consent is simultaneously the most important ethical safeguard in clinical research and the most frequently cited source of protocol deviations at clinical investigator sites. It is the mechanism through which a person's autonomy, their right to decide what happens to their own body, is respected in the research context. And it is the regulatory obligation that, when improperly handled, most directly reflects a failure of participant protection rather than a procedural technicality.

For Clinical Research Coordinators, understanding informed consent means understanding it at three levels: its ethical foundation, its specific regulatory requirements, and its practical implementation in the day-to-day workflow of participant contact. This guide covers all three.

Why Informed Consent Is the Cornerstone of Research Ethics

The requirement for informed consent in clinical research is not a regulatory formality: it is the direct response to documented historical abuses in which human beings were subjected to research without their knowledge or agreement. The Nuremberg Doctors' Trial (1946–1947) established that voluntary consent is absolutely essential in research involving human subjects. The Declaration of Helsinki (1964, revised most recently in 2013) codified informed consent as a fundamental requirement for ethical research. The Belmont Report (1979) grounded it in the principle of respect for persons, the recognition that individuals have the capacity for self-determination and that this capacity must be protected, not overridden, by researchers.

These historical and philosophical foundations are not merely background. They explain why consent violations are treated with such seriousness by regulatory authorities and IRBs. A protocol deviation that involves conducting a study procedure before obtaining informed consent is not a paperwork error. It is a failure to protect a participant's fundamental right to choose whether to participate in research.

The Regulatory Basis: 21 CFR Part 50 and 45 CFR Part 46

In the United States, informed consent in FDA-regulated clinical trials is governed by 21 CFR Part 50 — Protection of Human Subjects. The general requirement is established in 21 CFR 50.20: no investigator may involve a human being as a subject in research covered by these regulations unless the investigator has obtained the legally effective informed consent of the subject or the subject's legally authorized representative. This requirement applies before any study-specific procedure is performed, including screening procedures.

For federally funded research that does not fall under FDA jurisdiction, the parallel framework is the Common Rule, codified at 45 CFR Part 46. The 2018 revised Common Rule updated several consent requirements, including adding new elements and modifying waiver criteria. Most IRBs apply both frameworks, and most CRCs working on industry-sponsored trials primarily operate under 21 CFR Part 50, but understanding that the parallel Common Rule framework exists, and that some research falls under both, is foundational for any clinical research professional working in federally funded or FDA-regulated settings.

ICH E6(R3), finalized January 2025 and adopted by the FDA as final guidance in September 2025, provides additional GCP-level guidance on the consent process. E6(R3) frames consent as an ongoing dialogue rather than a one-time event, a framing that aligns with the regulatory requirement but provides more explicit operational guidance on how that dialogue should be maintained throughout a participant's study participation.

The Belmont Report Foundation

The Belmont Report, published by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research in 1979, established three ethical principles that underpin all modern research ethics, including the consent requirement:

Respect for Persons — individuals should be treated as autonomous agents, and individuals with diminished autonomy are entitled to additional protections. Informed consent is the primary expression of this principle in research practice: it respects each person's capacity to make an informed decision about their own participation.

Beneficence — researchers have an obligation to maximize possible benefits and minimize possible harms. The disclosure of risks in the consent process is a direct expression of this principle — participants cannot weigh expected benefits against potential harms without accurate information about both.

Justice, the benefits and burdens of research should be distributed fairly. The consent process must ensure that participants are not selected because of their vulnerability or convenience, and that the consent process is not coercive for populations with less power relative to the researcher.

For a deeper exploration of the Belmont Report and its three principles in the context of modern clinical research, see our Belmont Report deep dive.

The 8 Basic Elements of Informed Consent

Under 21 CFR 50.25(a), eight basic elements of information must be provided to every research subject during the consent process. These are not optional — every element must be present in the consent form and communicated to the participant before enrollment.

Additional Elements Under 21 CFR 50.25(b)

Beyond the eight basic elements, 21 CFR 50.25(b) specifies additional elements that must be provided to subjects "when appropriate." These include:

• A statement that the particular treatment or procedure may involve unforeseeable risks to the subject or to an embryo or fetus, if the subject is or may become pregnant
• Anticipated circumstances under which participation may be terminated by the investigator without the subject's consent
• Any additional costs to the subject that may result from participation
• The consequences of the subject's decision to withdraw and procedures for orderly termination
• A statement that significant new findings developed during the course of the research will be provided to the subject
• The approximate number of subjects involved in the study
• A statement that the subject's biospecimens may be used for commercial profit and whether the subject will or will not share in that profit
• A statement regarding whether clinically relevant research results will be disclosed to subjects

Additionally, for applicable clinical trials as defined in federal law, the consent form must include a statement directing participants to ClinicalTrials.gov, noting that a description of the trial will be available there per U.S. law.

The Consent Conversation: More Than a Signature

The consent form is the documentation of the consent process: it is not the consent process itself. 21 CFR 50.20 requires that consent be sought under circumstances that provide the prospective subject or representative sufficient opportunity to consider whether to participate and minimize the possibility of coercion or undue influence. Information must be provided in language understandable to the subject or the representative, and the conditions under which consent is obtained must not be coercive.

In practice, this means the consent conversation must include adequate time for the participant to read the form, ask questions, and consider their decision without pressure. The participant should not be asked to consent in an environment or under time pressure that undermines genuine voluntary choice, a seriously ill patient being asked to consent in an emergency room immediately before an urgent procedure is in a fundamentally different position than a participant being offered enrollment in a non-urgent outpatient study with a week to consider.

The language requirement is operationally significant. If a participant's primary language is not English, the consent process must be conducted in a language they understand. A translated consent form, or short-form consent with an interpreter, may be required. IRBs have specific requirements for non-English consent; always check your IRB's policy and follow your sponsor's procedures for non-English consent situations before they arise at your site.

Documentation Requirements

Under 21 CFR 50.27, informed consent must be documented by a written consent form approved by the IRB and signed and dated by the subject or the subject's legally authorized representative at the time of consent. A copy must be given to the person signing the form.

The documentation requirements that CRCs must verify for every enrolled participant:

• The correct version of the consent form was used, the version approved by the IRB and in effect at the time of consent
• The participant's signature and date are present
• The person obtaining consent's signature and date are present
• The date of consent precedes or is on the same date as the first study-specific procedure, a consent date after any study procedure is a major protocol deviation
• A signed copy was provided to the participant at the time of consent
• The signed original is maintained in the participant's source file
• A blank copy of the same version is maintained in the ISF

Consent as Ongoing Process, Not One-Time Event

Both 21 CFR Part 50 and ICH E6(R3) treat informed consent as an ongoing process throughout a participant's involvement in a trial, not a one-time event at enrollment. This means the participant's consent to continue must remain genuinely informed — they must receive new information that could affect their willingness to participate as it becomes available.

Under 21 CFR 50.25(b), one of the additional consent elements that must be provided when appropriate is a statement that significant new findings developed during the course of the research will be provided to the participant. This is not just a statement in the consent form: it is an obligation to actually communicate significant new information when it emerges. ICH E6(R3) explicitly describes consent as an ongoing dialogue and identifies participant engagement throughout study participation as a GCP consideration.

Practically, this means CRCs must understand that their role in consent does not end when the form is signed. Every visit is an opportunity to assess whether the participant still understands and consents to their participation, and to communicate any relevant new information about the study. A participant who asks during a visit whether they can stop participating should never be made to feel that stopping is difficult, discouraged, or will affect their care — voluntariness is not just a statement in the consent form, it is a standard for how the site team treats participants throughout the study.

Re-Consent: When a New Consent Is Required

Re-consent is required when changes to the study or new information arise that may affect a participant's willingness to continue. The specific triggers for re-consent include:

• Protocol amendments that change the procedures a participant undergoes, the risks they are exposed to, or other material aspects of their participation, any amendment that could affect a participant's decision must trigger re-consent for enrolled participants
• Updated Investigator's Brochure containing new safety information that could affect a participant's risk assessment
• New safety findings from the same or related studies that create new reasonably foreseeable risks
• Consent form expiration, if an IRB requires annual re-consent as a condition of continued enrollment
• New consent version approved by the IRB that contains material changes from the version the participant originally signed

The standard for whether re-consent is required is whether a reasonable person would want to know the new information before deciding whether to continue participation. When in doubt, consult your PI and sponsor, and document whatever decision is made and the reasoning behind it.

eConsent Under ICH E6(R3)

ICH E6(R3), finalized January 2025, explicitly addresses electronic consent (eConsent) as a valid and supported approach to obtaining and documenting informed consent. E6(R3)'s treatment of eConsent reflects its broader media-neutral framework — the standard is the quality of the consent process, not the medium in which it occurs.

The requirements for eConsent under E6(R3) mirror the requirements for paper consent: the participant must have adequate time and opportunity to review the information, ask questions, and make a voluntary decision. The electronic platform must ensure that participants can navigate at their own pace, cannot be rushed through required elements, and that the platform generates a reliable record of consent that includes date, time, and participant identity. Audit trail requirements for electronic consent systems are the same as for other electronic records in clinical trials.

The FDA's guidance on electronic informed consent provides additional operational guidance on how eConsent platforms can be implemented in compliance with 21 CFR Part 50 and applicable IRB requirements. If your site uses or is considering eConsent, both the FDA guidance and your IRB's specific requirements should be reviewed before implementation.

Consent Waivers: When Consent May Be Modified or Waived

Under limited circumstances, an IRB may waive or modify consent requirements. Under 21 CFR 50.22, an IRB may waive or alter some or all consent elements if: the investigation involves no more than minimal risk; the investigation could not practicably be carried out without the waiver; the waiver will not adversely affect the rights and welfare of subjects; and subjects will be provided with additional pertinent information after participation where appropriate.

A separate provision, 21 CFR 50.24, addresses emergency research where prospective consent cannot be obtained — research on life-threatening conditions where subjects cannot consent due to their medical condition, the intervention must be administered before a legally authorized representative can be reached, and specific community consultation and disclosure requirements have been met. This exception is narrow, highly regulated, and applies to a very specific category of emergency intervention studies.

Consent waivers are granted by the IRB, not by the sponsor or investigator. A site cannot decide independently that consent is not required. Any situation that appears to present a consent challenge, a participant who is unable to consent, a language barrier, an emergency presentation — should be escalated to the PI and to the IRB immediately.

The CRC's Specific Role in the Consent Process

The regulatory responsibility for obtaining informed consent rests with the investigator — specifically, with qualified personnel who have been delegated authority for consent by the PI. Not every CRC is delegated to obtain consent independently. Whether a CRC is authorized to obtain consent, assist in the consent process, or only support logistics is specified in the delegation of authority log and reflects the PI's assessment of the CRC's qualifications and training for that role.

Regardless of delegation level, every CRC is responsible for:

• Verifying that consent documentation is complete and correct before any study procedure is performed
• Confirming that the consent form version matches the current IRB-approved version at every visit
• Identifying consent updates or re-consent requirements and escalating them to the PI promptly
• Never performing any study-specific procedure, including a screening assessment, before confirming that valid consent is in place
• Treating participants as autonomous agents throughout their study participation, never making them feel that withdrawal would have consequences, never minimizing their questions or concerns

The Most Common Consent-Related Errors

Consent-related protocol deviations are consistently among the most serious findings in clinical investigator BIMO inspections and sponsor monitoring visits. The most common:

• Consent after study procedure: Any study activity, including screening labs, eligibility assessments, or questionnaires — performed before the consent form is signed. This is the single most serious consent deviation.
• Wrong consent version: Participant consented using an outdated version after the IRB approved a new version. This is the reason consent version tracking at every visit is not optional.
• Missing re-consent after amendment: Protocol amendment requiring re-consent was approved but affected enrolled participants were not re-consented before their next study procedure under the amended protocol.
• Person obtaining consent not delegated: A staff member obtained consent who was not listed on the delegation log as authorized to obtain consent, or whose authorization had expired.
• Consent signed but copy not provided: The participant was not given a copy of the signed consent form at the time of signing — a specific regulatory requirement under 21 CFR 50.27.
• Missing or undated signature: Either the participant's or the person obtaining consent's signature or date is absent from the form.