Informed consent and loss of chance: the new basis for assessing damages in Supreme Court Judgment 374/2026
Judgment 374/2026 of 10 March of the “Tribunal Supremo” —Spain's Supreme Court— introduces an important refinement in medical civil liability where informed consent has been breached without any technical malpractice. In a case of vaginal birth after a previous caesarean, the lower courts had compensated the lack of information as free-standing non-pecuniary damage (“daño moral”), in amounts of around 10,000 to 15,000 euros, detached from the serious bodily injury suffered by the daughter. The Supreme Court corrects that approach and applies the doctrine of loss of chance, shifting the focus towards what the patient might have decided had she received full information. Quantification comes to depend on the seriousness of the risk not disclosed, on the therapeutic alternatives, on whether the medicine was necessary or elective and on the probability that the patient would have refused the procedure.
1.The case: vaginal birth after caesarean, with no technical malpractice but an informational deficit
STS 374/2026, a judgment of the “Tribunal Supremo”, Spain's Supreme Court, determines a cassation appeal brought by a patient and her minor daughter against the judgment of the “Audiencia Provincial”, the provincial appeal court, which had upheld, with some qualifications, the decision at first instance in a case concerning care during childbirth. The patient, with a history of a previous caesarean, underwent an attempted vaginal birth after caesarean in accordance with the protocols of the “Sociedad Española de Ginecología y Obstetricia”, the Spanish society of gynaecology and obstetrics, and in the course of labour a uterine rupture occurred which caused severe ischaemic encephalopathy in the daughter.
Both the court of first instance and the provincial appeal court ruled out technical malpractice in the care given during childbirth. They held that the obstetric management complied with the lex artis as regards the indication for, the monitoring of and the handling of the vaginal birth after caesarean. They found, however, that the right to informed consent had been breached, in that the patient had not been given sufficient information about the specific risks of vaginal birth after caesarean, about the alternative of a further elective caesarean, or about the likelihood of success and of complications under each option. The information was insufficient and did not allow a free and fully aware decision.
The lower courts treated that breach as free-standing non-pecuniary damage (“daño moral”), detached from the bodily injury suffered by the daughter, and awarded 10,000 euros under that head. On hearing the appeal, the Supreme Court maintains that there was no technical malpractice, but corrects the approach to damages and applies the doctrine of loss of chance.
2.Informed consent as part of the lex artis and the distinction between technical and informational malpractice
STS 374/2026 reaffirms that informed consent forms part of the lex artis ad hoc. Law 41/2002, the “Ley básica reguladora de la autonomía del paciente” —the basic act governing patient autonomy— provides that any intervention in the field of health requires the prior free and voluntary consent of the patient, once the patient has received adequate information about the purpose and the nature of the procedure, its risks and its consequences. The information must be truthful, intelligible and suited to the patient's needs, and must help the patient to take decisions in accordance with their own free will.
The Court draws a clear distinction between technical malpractice and breach of the lex artis informativa, the duty to inform. The former concerns errors in diagnosis, in the therapeutic indication or in the performance of the technique, which directly give rise to bodily injury. The latter concerns the omission or the insufficiency of the information the patient needs in order to decide whether or not to undergo the medical procedure. In the case under analysis, no technical malpractice was established in the care given during childbirth, but there was a breach of the lex artis informativa, in that the risks of vaginal birth after caesarean and the alternative of an elective caesarean had not been properly explained.
That distinction makes it possible to separate the analysis of the bodily injury, which in the absence of technical malpractice cannot be attributed directly to the medical treatment, from the analysis of the harm flowing from the lack of information, which is tied to the loss of the possibility of deciding otherwise. The Court rejects the compensation of the breach of informed consent as a fixed, free-standing head of non-pecuniary damage detached from the bodily injury, and opts instead for the doctrine of loss of chance.
3.From free-standing non-pecuniary damage to loss of chance: a change in the basis for assessing damages
The lower courts had taken the view that the lack of information gave rise to free-standing non-pecuniary damage, consisting in the impairment of the patient's dignity and autonomy, and had assessed it at a fixed sum. The Supreme Court corrects that approach. It holds that, where there is an informational deficit without technical malpractice, the compensable harm is not a mere abstract non-pecuniary damage but the loss of the chance of avoiding or reducing the bodily injury, to the extent that the patient's decision might have been different had they been properly informed.
The doctrine of loss of chance, well established in healthcare liability, applies where the medical treatment omitted or defectively performed deprives the patient of a real, and not merely speculative, possibility of cure, survival or avoidance of harm. In such cases the compensable harm is not the bodily injury in its entirety but the loss of the prospect of a better outcome. Damages are calculated as a fraction of the total harm, by reference to the probability that correct treatment would have avoided or mitigated it.
In STS 374/2026 the Court transposes that logic to informed consent. The question becomes what the patient might have decided had she received full information about the risks of, and the alternatives to, vaginal birth after caesarean. Damages are not set as a fixed sum for non-pecuniary damage but as a percentage of the total bodily injury, reflecting the probability that the patient would have chosen the less risky alternative and avoided the harm.
4.Weighing the factors: seriousness of the risk, alternatives, necessary or elective medicine and the probability of refusal
In order to quantify the loss of chance, the Supreme Court carries out a prospective assessment and weighs several factors. First, the seriousness of the risk not disclosed. Vaginal birth after caesarean carries a higher risk of uterine rupture than an elective caesarean, although in absolute terms that risk is low. The evidence put before the court indicated that the probability of uterine rupture in vaginal birth after caesarean stood at around 0.32‑0.47 per cent, whereas in elective caesarean it was approximately 0.03 per cent. The difference is significant, although both risks are statistically infrequent.
Secondly, the therapeutic alternatives. In the case under analysis there were two reasonable options: vaginal birth after caesarean, recommended by the protocols as the preferred option in certain conditions, and elective caesarean, carrying a lower risk of uterine rupture but other associated risks. The medicine was necessary, in the sense that the birth had to take place, but the choice between the two routes was not strictly dictated; there was scope for an informed decision by the patient.
Thirdly, whether the medicine was necessary or elective. Academic commentary has stressed that loss of chance carries a different weight in elective or cosmetic medicine, where the patient could have avoided the intervention altogether, than in necessary medicine, where the alternative is usually another intervention or treatment. In the case of childbirth the intervention is necessary, but the mode of delivery is a matter of choice, which justifies applying loss of chance in terms of a choice between alternatives.
Fourthly, the probability that the patient would have refused the procedure. The Court must assess, on the basis of the evidence and of experience, whether a patient properly informed about the risks and the alternatives would have opted for an elective caesarean. This is not a matter of certainty but of probability. The Chamber sets that probability at 20 per cent, taking the view that, although vaginal birth was the recommended option and had a high probability of success, the existence of a serious risk, albeit an infrequent one, could have led some patients to choose a caesarean.
On that basis the Court sets the award at 20 per cent of the total harm established. That translates into 200,000 euros for the daughter and 1,077.96 euros for the mother, plus the late-payment interest under article 20 of the “Ley de Contrato de Seguro”, Spain's insurance contract act. The award reflects the loss of the chance of avoiding the harm, not the bodily injury in full.
5.The distinction between bodily injury, non-pecuniary damage and loss of chance
STS 374/2026 makes it possible to distinguish clearly between several categories of harm in medical liability. Bodily injury is the physical or psychological harm suffered by the patient, in this case the daughter's severe ischaemic encephalopathy and the mother's lasting physical and psychological effects. Technical malpractice, where it exists, is attributed directly to that bodily injury, and damages are calculated on the whole of the harm, in accordance with the applicable scale of assessment.
Non-pecuniary damage is the impairment of the patient's emotional sphere, dignity or autonomy, which may flow both from the bodily injury and from the breach of fundamental rights, such as the right to information and to autonomy. In some cases the case law has recognised free-standing non-pecuniary damage for want of informed consent, even in the absence of significant bodily injury, particularly in elective or cosmetic medicine.
Loss of chance lies on an intermediate plane. It is neither bodily injury in itself nor abstract non-pecuniary damage, but the loss of a real possibility of avoiding or reducing the bodily injury. In the context of informed consent, loss of chance refers to the loss of the possibility of deciding otherwise and avoiding the harm, where the patient's decision might have been different had they been properly informed.
STS 374/2026 opts for loss of chance as the basis for assessing damages where informed consent is lacking without technical malpractice, shifting the approach from a fixed sum for non-pecuniary damage towards an award proportionate to the bodily injury and to the probability that the decision would have been different. That choice reinforces the link between breach of the lex artis informativa and the bodily injury, without requiring the harm to be attributed in full, while preventing the breach of informed consent from being reduced to symbolic non-pecuniary damage.
6.Conclusion: informed consent, the lex artis informativa and loss of chance
STS 374/2026 lays down a new basis for assessing damages in medical liability where informed consent is lacking without technical malpractice. Informed consent is reaffirmed as part of the lex artis, and its breach gives rise to liability, but the award is not framed as a fixed, free-standing head of non-pecuniary damage; it is framed as loss of chance. The central question becomes what the patient might have decided had they received full information, and quantification requires weighing the seriousness of the risk not disclosed, the therapeutic alternatives, whether the medicine was necessary or elective and the probability of refusal.
The judgment makes it possible to distinguish precisely between technical malpractice, breach of the lex artis informativa, bodily injury, non-pecuniary damage and loss of chance, and it offers a more finely tuned tool for compensating cases in which the medical treatment is technically correct but the patient's autonomy has been infringed. For litigation practice, loss of chance is consolidated as the reference point in informed consent disputes, requiring a close analysis of the alternatives, of the risks and of the patient's potential decisions, and avoiding simplistic solutions based on uniform awards for non-pecuniary damage.
