The principle of double effect in palliative care: a systematic review of ethical, legal, and clinical perspectives.

backgroundThe Principle of Double Effect (PDE) has historically been used to justify medical interventions intended to relieve suffering, even when such treatments may carry a foreseeable risk of hastening death. In palliative care, the doctrine is particularly relevant to opioid administration and palliative sedation. However, its relevance and practical importance remain debated in contemporary clinical and ethical discourse.

objectiveThis systematic review aims to examine how the Principle of Double Effect is interpreted and applied in palliative care literature, with a focus on ethical, legal, and clinical perspectives.

methodsA systematic search was conducted in PubMed/MEDLINE, Scopus, Web of Science, and Embase. Studies addressing the Principle of Double Effect in the context of palliative or end-of-life care were included. Titles and abstracts were screened, followed by full-text assessment based on predefined inclusion criteria. Data were extracted using a standardized form and synthesized using a thematic narrative approach. The review followed PRISMA guidelines.

resultsThirty studies met the inclusion criteria. The included literature comprised ethical analyses, clinical reviews, empirical studies, and clinical guidelines, primarily originating from Europe and North America. The Principle of Double Effect was most frequently discussed in relation to opioid administration for pain and dyspnea, palliative sedation for refractory symptoms, and the ethical and legal distinction between symptom relief and life-ending practices. Evidence suggests that appropriately titrated opioids rarely shorten life, reducing reliance on the doctrine in this context. In contrast, palliative sedation remains more ethically complex, and the principle continues to play a more prominent role in its justification. While some authors support the doctrine as an important ethical safeguard, others question its practical applicability in contemporary clinical practice.

conclusionThe Principle of Double Effect remains a central concept in ethical discussions of end-of-life care, particularly in distinguishing symptom relief from intentional life-ending practices. However, its practical relevance is context-dependent and evolving. Further empirical research examining how clinicians interpret and apply the principle in practice is needed to clarify its role in modern palliative care.