Sliding or securing? Emotional ambivalence and public perception after euthanasia legalization in Japan

This study examined how legislation regarding euthanasia legalization influences individuals' psychological responses, focusing on slippery slope concerns and expectations regarding human dignity. In a preregistered experiment, 294 Japanese adults were recruited online and randomly assigned to legalization or control conditions; the final sample comprised 230 adults. Participants in the legalization condition read a simulated news article about the enactment of a euthanasia law; the control group received no such framing. Results contradicted initial hypotheses; legalization significantly decreased slippery slope concerns and did not affect dignity expectations. Even in scenarios outside legal boundaries-including depression or poverty-support for euthanasia increased, indicating a "slippery slope" beyond institutional limits. This study provides preliminary evidence that emotional ambivalence shapes public responses to end-of-life legislation. Presenting legal frameworks clearly can build trust and reduce concerns about ethical drift. The findings highlight the importance of affective mechanisms in designing and communicating ethically sensitive public policies.