Research on coercion in mental healthcare has recently shifted to the investigation of subjective aspects, both on the side of the people with mental disorders affected and the staff members involved. In this context, the role of personality traits and attitudes of staff members in decision-making around coercion is increasingly being assessed. We developed and validated a German version of the Staff Attitudes towards Coercion Scale and then used it in an experimental case vignette study. Results from both studies showed that attitudes towards coercion – ranging from rejecting to approving the use of coercion – significantly influenced decisions around coercion in individuals cases, resulting in a greater likelihood to approve of the use of coercion. Strategies to reduce coercion in mental healthcare institutions should focus more on the role of staff attitudes and encourage staff members to reflect on them critically.