1. Meaning 

Consent drift in adaptive therapies refers to the gradual divergence between the treatment a patient originally consented to and the treatment that is subsequently delivered as the therapy changes over time.

It is particularly relevant to treatments that are repeatedly adjusted in response to a patient's biological data, genetic profile, brain activity, clinical response, artificial-intelligence recommendations, or real-time monitoring.

Unlike a single medical intervention, an adaptive therapy may evolve through multiple treatment cycles. The original consent may authorize one intervention, but later adjustments can change its dosage, technical method, risk profile, data use, or therapeutic objective.

Example: A patient consents to an AI-assisted neurological treatment involving non-invasive brain stimulation. Over several months, the system begins using additional neural data, changes stimulation parameters, and introduces a predictive algorithm that was not explained when consent was obtained. Even if the treatment remains medically beneficial, the changes may raise questions about whether the patient's original consent still covers the intervention.

Consent drift is not, by itself, a universally recognized, independent cause of action. It is a useful legal and ethical concept for analysing whether consent remains informed, voluntary, specific, and valid as treatment evolves.

2. Principal forms of consent drift

A. Therapeutic drift

The treatment's purpose or clinical approach changes beyond what the patient reasonably understood or authorized. For example, a therapy originally intended to reduce symptoms is adapted to pursue a substantially different outcome.

B. Parameter drift

Dosage, stimulation intensity, frequency, or treatment duration changes. Routine adjustments within an explained treatment plan may be covered by consent; material or unexpected changes may require renewed disclosure and authorization.

C. Algorithmic drift

A machine-learning system changes its recommendations, model, or decision process after deployment, potentially altering treatment in ways not anticipated during the original consent process.

D. Data-use drift

Clinical data collected for treatment are later used for model training, research, commercial development, or additional profiling without adequate authorization.

E. Risk drift

New evidence, unexpected side effects, or changed treatment conditions materially alter the balance between benefit and harm. Previously adequate disclosure may no longer be sufficient.

3. Legal foundations

Consent drift is best analysed through established doctrines rather than assumed to be a separate legal category.

A. Informed consent

A patient should receive information material to the decision to undergo treatment, including relevant risks, alternatives, and the nature of the proposed intervention. The precise requirements depend on the jurisdiction and circumstances.

Where a therapy adapts within an agreed clinical range, fresh consent for every minor adjustment may be unnecessary. However, a substantial change in the intervention, its risks, or its purpose can require renewed consent.

B. Continuing consent

Consent to an ongoing course of treatment is not necessarily unlimited permission for every future intervention. The legal question is whether the subsequent treatment remains within the scope of the authorization originally given.

Continuing consent is particularly important where adaptive systems make repeated decisions without a clinician discussing each change individually.

C. Patient autonomy and bodily integrity

A competent adult's right to make decisions about medical treatment limits the extent to which clinicians may substitute their own judgment for the patient's informed choice.

Clinical benefit does not automatically cure a failure to obtain legally required consent.

D. Confidentiality and data protection

Consent to receive treatment is distinct from consent to use identifiable health data for unrelated purposes. Depending on the applicable law, separate legal grounds, disclosures, safeguards, or permissions may be required.

E. Professional negligence

Even when consent exists, clinicians and healthcare providers may be liable if treatment adjustments fall below the applicable standard of care, foreseeable risks are inadequately managed, or material developments are not communicated when required.

4. Leading case laws

The following judgments establish principles that can be applied to consent drift. They do not all concern adaptive therapies directly; their relevance lies in the legal rules governing disclosure, consent, autonomy, and unauthorized changes to treatment.

Case 1: Samira Kohli v. Dr. Prabha Manchanda (2008) 2 SCC 1

Indian Supreme Court

Facts: The patient consented to a diagnostic procedure. During surgery, the doctor performed additional, more extensive surgery without obtaining her specific consent.

Legal issue: Could consent to one procedure authorize a different procedure merely because the doctor considered the additional intervention beneficial?

Held: The Supreme Court emphasized that valid consent must be voluntary, given by a competent patient, and based on adequate information about the proposed treatment. Consent for diagnosis does not ordinarily authorize an unrelated or materially different therapeutic procedure. The exception for necessary additional intervention is narrow, particularly where an emergency makes delay unreasonable.

Indian Kanoon+1

Application to consent drift: This is one of the strongest Indian authorities for the proposition that an initial authorization has boundaries. A clinician cannot assume that permission for an adaptive treatment automatically extends to every later modification.

Case 2: Montgomery v. Lanarkshire Health Board [2015] UKSC 11

United Kingdom Supreme Court

Facts: An obstetrician failed to adequately disclose a material risk associated with vaginal delivery and the alternative of a caesarean section.

Legal issue: Should disclosure be determined solely by professional medical practice, or must the patient's right to make an informed choice be respected?

Held: Doctors must take reasonable care to ensure that patients understand material risks and reasonable alternative treatments. A risk is material if a reasonable person in the patient's position would likely attach significance to it, or if the doctor knows or ought to know that this particular patient would do so.

Bailii+1

Application to consent drift: When an adaptive therapy develops a newly material risk, the clinician cannot necessarily rely on the original consent form. The relevant question is whether the patient has been adequately informed about the treatment as it now stands.

Case 3: Canterbury v. Spence 464 F.2d 772 (D.C. Cir. 1972)

Court: United States Court of Appeals for the District of Columbia Circuit.

Facts: The patient suffered serious complications after spinal surgery and alleged that he had not been adequately informed of relevant risks.

Legal principle: The court articulated a patient-centred approach to disclosure, emphasizing that material risks and available alternatives are important to a meaningful decision.

Application to consent drift: If a treatment algorithm introduces a material new risk or changes the balance between benefits and harms, the treating team should reassess whether the patient's original decision remains informed. The precise disclosure standard depends on the jurisdiction.

SC)+1

Case 4: Rogers v. Whitaker (1992) 175 CLR 479

Court: High Court of Australia.

Facts: A patient suffered a serious complication affecting her previously healthy eye following surgery on the other eye. The surgeon had not adequately warned her about that risk.

Held: The court recognized the importance of disclosing risks that a reasonable person in the patient's position would consider significant, as well as risks the doctor knows or should know the particular patient would consider significant.

Application to consent drift: Personalized adaptive therapies make individual preferences especially important. A risk that appears statistically small may nevertheless be significant to a particular patient—for example, a potential cognitive effect in a person whose occupation depends on precise memory or concentration.

Bailii+1

Case 5: Schloendorff v. Society of New York Hospital 105 N.E. 92 (N.Y. 1914)

Court: New York Court of Appeals.

Facts: A patient consented to an examination under anaesthesia but did not authorize the surgical removal of a tumour.

Legal principle: The judgment is historically associated with the principle that a competent adult has the right to determine what is done to their body.

Application to consent drift: An adaptive system's technical capacity to change a treatment does not itself confer legal authority to make every possible change. Authorization and clinical decision-making must remain within legally permissible boundaries.

Case 6: Sidaway v. Board of Governors of the Bethlem Royal Hospital [1985] AC 871

Court: House of Lords, United Kingdom.

Legal principle: This earlier decision applied a more professionally oriented approach to disclosure of medical risks. Its significance today is largely historical because Montgomery subsequently established a more patient-centred approach in UK law.

Application to consent drift: The case illustrates the evolution from treating disclosure primarily as a matter of medical professional judgment toward recognizing the patient's independent right to make informed choices.

Scottish Parliament Website+1

Case 7: Yash Charitable Trust v. Union of India (2026 INSC 96, decided 30 January 2026)

Recent Indian Supreme Court authority

Facts: The case concerned the promotion and administration of stem-cell interventions for autism spectrum disorder (ASD) outside approved and monitored clinical trials.

Legal issue: Can a patient's or guardian's consent make an inadequately validated treatment legally permissible as a routine clinical service?

Held: The Supreme Court held that stem-cell therapy for ASD could not be offered as a routine clinical service outside an approved and monitored research or clinical-trial setting. It explained that voluntary choice alone does not amount to valid informed consent where adequate information about the intervention is lacking. The Court also addressed regulatory safeguards for such research. 【turn775001search0】【turn775001search8】

Application to consent drift: This decision is particularly relevant to adaptive and experimental therapies. Even repeated consent, a signed consent form, or a patient's willingness to continue cannot automatically cure fundamental deficiencies in scientific validation, disclosure, or regulatory compliance.

It establishes an important distinction: consent authorizes a legally permissible intervention; it does not independently make an unsafe, unvalidated, or unlawful intervention permissible.

5. Comparative legal position

These authorities offer comparative guidance, but the precise legal test, available remedies, and regulatory requirements differ across jurisdictions.

6. When does an adaptive change require renewed consent?

The key distinction is between a change already contemplated by valid consent and a material departure from the agreed treatment.

Ordinary adjustment within the agreed plan

A clinician adjusts dosage within a disclosed range, consistent with the treatment plan and applicable standards of care. Fresh consent for every adjustment may not be necessary, although monitoring and appropriate communication remain important.

Material change in risks or treatment purpose

A therapy introduces a significant new risk, a different intervention, a substantially altered therapeutic objective, or a new use of personal health data. Updated disclosure and renewed consent may be required.

Change beyond the authorized scope

A provider introduces an unauthorized intervention or uses a system in a manner that violates applicable legal or regulatory requirements. The original consent is not a blanket defence.

No universal numerical threshold determines when a change becomes material. The assessment depends on the nature of the intervention, its risks, the patient's circumstances, the original consent, and the applicable law.

7. Legal liability arising from consent drift

Consent drift can produce several forms of legal exposure.

Negligence: Failure to communicate material risks, monitor treatment changes, or meet the applicable standard of care.

Unauthorized treatment: Performing a materially different procedure without adequate authorization may give rise to claims based on battery, trespass to the person, or other applicable legal doctrines.

Deficient consent documentation: Inadequate records may make it difficult to demonstrate what the patient was told and what they authorized.

Privacy and data-protection violations: Reusing sensitive medical or neural data beyond the scope of authorization may breach applicable privacy law.

Regulatory liability: Using an adaptive medical device or experimental intervention outside applicable approval, research, or monitoring requirements can trigger separate regulatory consequences.

Institutional responsibility: A hospital, research sponsor, or technology provider may face liability where its own acts or omissions contribute to unauthorized treatment, subject to the governing law.

Importantly, a consent defect does not automatically establish every element of a negligence claim. The applicable cause of action, causation requirements, and available damages must be considered separately.

8. Practical safeguards against consent drift

Healthcare providers, researchers, and developers can reduce legal risk through a structured consent-management system.

Initial consent: Explain the therapy's purpose, expected benefits, material risks, alternatives, foreseeable adaptations, and relevant data uses.

Defined adaptation boundaries: Document which changes may be made routinely and which require further discussion or authorization.

Change-triggered review: Reassess consent when a material new risk emerges, the treatment objective changes, or the intervention moves beyond the original scope.

Human oversight: Ensure that clinically significant automated recommendations can be reviewed by an appropriately qualified professional.

Version-controlled records: Record the treatment plan, material changes, explanations given, patient decisions, and the relevant system or model version.

Withdrawal mechanisms: Make it practical for patients to refuse future adaptations or withdraw consent where legally permissible, while explaining any consequences and limitations.

Independent safeguards: For research and experimental interventions, comply with applicable ethics-review, trial-approval, monitoring, and reporting requirements.

These are recommended safeguards, not a claim that every jurisdiction imposes identical documentation or re-consent obligations.

9. Illustrative legal analysis

Suppose a patient enters an adaptive gene-based treatment programme after receiving information about its initial risks and intended benefits. After several treatment cycles, the system recommends a different intervention that has a substantially different risk profile.

The legal analysis would ask:

Did the original consent clearly cover that type of adaptation?

Was the new risk material to the patient's decision?

Was the change clinically justified and consistent with applicable standards?

Was the patient given a meaningful opportunity to accept or refuse the revised intervention?

Did the revised treatment require regulatory or research approval?

Did any failure to disclose or obtain consent cause a legally recognizable injury?

If the change was material, foreseeable, and outside the authorization given, the provider may face a stronger claim for inadequate consent or unauthorized treatment. Conversely, a routine, properly monitored adjustment within an adequately explained plan is less likely to require an entirely new consent process.

10. Conclusion

Consent drift presents a significant challenge to conventional medical-consent doctrine because adaptive therapies can evolve after the patient has made the initial decision to undergo treatment.

The central legal principle is that consent must remain adequate for the intervention actually delivered, not merely the intervention originally described. Samira Kohli establishes important boundaries on treatment authorization in India; Montgomery emphasizes disclosure of material risks; and Yash Charitable Trust (2026) confirms that patient choice cannot substitute for adequate information and lawful medical practice.

Together, these cases support a model of consent that is responsive to material changes while avoiding the impractical requirement of obtaining fresh consent for every minor clinical adjustment.

For a more focused legal analysis, the next useful step would be to examine consent drift in adaptive therapies under Indian law specifically, including Article 21, medical negligence, clinical-trial regulation, and relevant Supreme Court precedents.