People who interact with citizens in their job often have to use discretion when facing complex situations. Research shows that how people understand their job regulates this use of discretion. Yet, little research has conceptualized how group culture shapes these understandings and discretionary actions in real-life citizen encounters. This article addresses this gap with a microsociological theory of group culture. To demonstrate the merits of this theory, I use a sample of 11 interviews and 88 body-worn camera recordings to analyze how ticket inspectors perceive and act in contested ticket-fining events. The analysis identifies two group styles of moral inspection characterized by tight or loose regulation: justice or service. These styles are associated with the two operating teams in a traffic company and influence how inspectors manage contested events with a risk of escalation. I discuss how these findings contribute to the sociology of culture and enhance the understanding of how group culture shapes discretionary actions in citizen encounters.