Police responses to juvenile brawls must protect public safety while preserving the rights, dignity, and developmental interests of children in conflict with the law. This article examines how organizational ethical culture shapes police handling of juvenile brawls in Semarang and develops a case-based model for institutional change. Ethical culture is operationalized through the alignment of formal policies, everyday practices, supervisory example, peer norms, complaint control, and disciplinary accountability. The study uses a qualitative instrumental single-case design at Polrestabes Semarang. The dataset comprises semi-structured interviews with police personnel and officials, children and families, oversight actors, local-government representatives, legal-aid and community stakeholders, together with complaint materials, case-related documents, regulations, and institutional records collected from February to September 2025. Data were interpreted through interactive qualitative analysis and source-method triangulation. The findings identify divergent operational orientations within the same organization. Coercive responses were reported more frequently in patrol and public-order encounters, whereas specialist Women and Children Protection Unit practices were more protective, communicative, and legally oriented. The divergence is not treated as a fixed warrior-guardian binary; it reflects context-dependent orientations reinforced by differences in competence, leadership, peer expectations, workflow, procedural guidance, and supervision. The article's contribution is an integrated Ethical Culture Change Model that links the substantive content of ethical culture to Lewin's change sequence and four systemic intervention targets: individual capability, social norms, work methods, and organizational governance. The model translates the case findings into operational instruments for training, PPA coordination, use-of-force review, complaint handling, supervision, and continuous evaluation.