Consent models: opt-in vs opt-out (presumed consent)

Consent models for deceased organ donation describe how a country establishes legal authorization to recover organs after death. The two principal models are opt-in (explicit consent), in which a person must affirmatively register or otherwise record a wish to donate, and opt-out (presumed or "deemed" consent), in which donation is permitted unless the person registered an objection during life.[1] The United States uses an opt-in system based on first-person authorization under the Uniform Anatomical Gift Act (UAGA), while many European countries operate some form of opt-out.[1][2]

The comparative effectiveness of these models is one of the field's genuinely contested empirical questions. Opt-out countries tend to report higher deceased-donation rates, but the best available evidence suggests that the consent law alone does not explain those differences; organizational and infrastructural capacity, donation coordinators, intensive-care practices, and a supportive culture, appears decisive.[1][2] This article describes both models, their international variants, the efficacy evidence, the role of families, and the surrounding ethical debate, presented from a neutral point of view and with proportionate weight to the strength of the evidence.

Opt-in (explicit consent)

Under an opt-in model, a person becomes a registered donor only by an affirmative act, joining a donor registry, designating donation on a driver's license, or otherwise recording the decision during life.[1] In the United States this is implemented as first-person authorization under the UAGA: a documented donor registration is a legally binding decision that does not require additional family approval, and absent such a record, authorization is sought from a legally authorized surrogate in a defined priority order.[3] The United Kingdom historically used an opt-in model built around the NHS Organ Donor Register before several of its nations moved to opt-out.[1]

The chief argument for opt-in is that it most clearly respects individual autonomy: donation proceeds only where the person (or a surrogate) has affirmatively chosen it.[1] The chief practical limitation is that registration rates are often well below the share of the public that supports donation in principle, leaving many potential donors with no recorded decision.[1][2]

Opt-out (presumed or deemed consent)

Under an opt-out model, every adult is presumed to consent to donation unless they have registered a refusal during life. The literature distinguishes two forms:[1]

• Hard opt-out: organs may be recovered unless the individual opted out, and the family has no role in the decision.
• Soft opt-out: there is a legal presumption in favor of donation, but the family is consulted and in practice may decline. Most countries that adopt opt-out use the soft form.[1]

Opt-out is also called presumed consent or, in the United Kingdom, deemed consent. A central question for any opt-out system is whether the presumption is genuinely operative or whether, in practice, families are still approached and their wishes still respected, which makes many "opt-out" systems function much like opt-in at the bedside.[1]

International examples

Spain is the most-cited high-performing system and is frequently, but inaccurately, attributed to presumed consent. Spain enacted opt-out legislation in 1979 with no apparent effect on donation rates; its donation rate rose only after 1989, when the national transplant organization (Organización Nacional de Trasplantes, ONT) was established and medically qualified donor coordinators were placed in every hospital.[1][4] In practice Spain does not operate an opt-out registry, there is no register for people to opt in or out, and consent is obtained explicitly from the patient (in life) or the family.[1] Spain has long reported the world's highest deceased-donation rate per million population, a result its own authorities attribute to the in-hospital coordinator model and intensive-care practices rather than to the consent law.[4]

United Kingdom. Three UK nations moved from opt-in to a soft opt-out ("deemed consent") model in succession: Wales in December 2015, England on 20 May 2020 (the Organ Donation (Deemed Consent) Act, known as "Max and Keira's Law"), and Scotland in March 2021.[5] In each case the system is explicitly soft: specialist nurses support families in reaching a decision based on what the person would have wanted, and a family's decision against donation is honored.[5] In Wales, donor numbers were almost unchanged in the first full year after the 2015 change.[1]

Many other European countries (for example France, Belgium, Austria, and Portugal) operate opt-out systems of varying strictness, while several (including Germany) retain opt-in. Donation rates vary widely within both groups, which complicates any simple attribution of performance to the consent model.[1][2]

The efficacy evidence

Multiple systematic reviews have examined whether switching from opt-in to opt-out raises deceased-donation rates, and the consistent finding is that the evidence is weak and confounded.[1][2] An influential review by Rithalia and colleagues (2009) concluded that publications suggesting a benefit from presumed consent "have important methodological flaws that make it very difficult to isolate the impact of the law" from other changes occurring at the same time.[1] Later reviews reached compatible conclusions: opt-out legislation is associated with higher donation rates in cross-country comparisons, but the association is confounded by differences in transplant infrastructure, intensive-care capacity, public attitudes, and investment in donation programs, so a causal effect of the law alone cannot be isolated, and any independent effect appears marginal.[1][2] Analyses modeling the policy change directly have likewise found that the capacity of opt-out laws to increase the number of donors is limited.[2]

The Spanish case is the standard illustration of why consent law is not the decisive variable: the law preceded the rise in donation by a decade, and the rise tracked organizational reforms (the ONT, hospital coordinators, and ICU practices), not the legislation.[1][4] The widely shared inference is that organizational and infrastructural capacity, rather than the consent model, is the primary driver of deceased-donation rates, a conclusion that the comparative literature treats as the most defensible reading of the evidence.[1][2] This does not establish that opt-out has no effect; it establishes that the law alone is, at most, one modest factor among several and is not a substitute for building donation infrastructure.[1][2]

The role of the family

Under both models, families are usually involved in practice. In opt-in systems, families of potential donors are routinely approached regardless of registration status; agreement is substantially higher when the patient had registered (on the order of ~90%) than when they had not (~70%), which is one argument advanced for registration and for opt-out defaults.[1] In soft opt-out systems, the family is still consulted and may decline, so the practical difference from opt-in can be smaller than the legal change suggests.[1][5] In hard opt-out systems, the family has no formal role, but few countries operate a strictly hard model in practice.[1] Because most real-world systems consult families, family refusal rates and the quality of the donation conversation are major determinants of donation outcomes under either model.[1]

Ethical debate

The debate over consent models pits two values against each other. Proponents of opt-in emphasize autonomy: donation should rest on an affirmative choice, and presuming consent risks recovering organs from people who never decided. Proponents of opt-out frame the default as a nudge that better reflects majority preferences, surveys typically show far more public support for donation than registration rates capture, while still allowing anyone to refuse, so individual choice is preserved.[1] Soft opt-out is often presented as a compromise that changes the default in favor of donation without overriding families. Critics on both sides note that a poorly communicated opt-out change can reduce public trust if people feel the state is "taking" organs, which underscores that public engagement and infrastructure, not the legal default, do most of the work.[1][2]

United States context

The United States retains an opt-in, first-person-authorization model under the UAGA and the National Organ Transplant Act (NOTA) framework, supported by state donor registries and the National Donate Life Registry (see Donor registry and Donate Life America).[3] Proposals to adopt presumed consent have been raised periodically but not enacted, and U.S. policy attention has concentrated instead on organizational and performance reforms, for example, outcome-based metrics for organ procurement organizations, consistent with the evidence that capacity, rather than the consent default, is the principal lever on donation rates.[1][2]

See also

• Organ donation
• Uniform Anatomical Gift Act (UAGA)
• National Organ Transplant Act (NOTA)
• Donor registry and Donate Life America
• The donation pathway

References

• Organ donation: opting in or opting out? PMC5774938. https://pmc.ncbi.nlm.nih.gov/articles/PMC5774938/
• Opt-out policies' capacity to increase organ donors is limited. medRxiv 2021.08.27.21262033. https://www.medrxiv.org/content/10.1101/2021.08.27.21262033v3.full
• Uniform Anatomical Gift Act and first-person authorization. StatPearls NBK470922. https://www.ncbi.nlm.nih.gov/books/NBK470922/
• The Spanish Model and the Organización Nacional de Trasplantes (ONT). PMC10249502. https://pmc.ncbi.nlm.nih.gov/articles/PMC10249502/
• NHS Blood and Transplant. Max and Keira's Law comes into effect in England (deemed consent dates: Wales 2015, England 20 May 2020, Scotland March 2021; soft opt-out). https://www.nhsbt.nhs.uk/news/max-and-keira-s-law-comes-into-effect-in-england/