Joint decision makingJoint decision making in team interaction is key to successful healthcare. In such a context, the leader’s rejection of a colleague’s proposalProposal could happen, which could be face-threatening (Brown and Levinson in Politeness: some universals in language usage. Cambridge University Press, 1987; Goffman in Psychiatry 18:213–231, 1955). This chapter multimodally analyses team interactions in emergency care simulationEmergency care simulation in two different sociocultural contexts, Japan and the UK, capturing the moment when a team leader rejectsReject a member’s proposal of future actions. Drawing on the notion of deontic authorityDeontic authority (Stevanovic and Peräkylä in Research on Language and Social Interaction 45:297–321, 2012), the negotiation of their deonticityDeonticity and epistemicityEpistemicity in interprofessional (intercultural) communication is cross-culturally investigated. Four simulation training sessions (two each on both sites) were filmed with video cameras and an eye-tracking deviceEye-tracking device, which was worn by the team leader. In the four data sets, about 50 occurrences of members’ proposalsProposal were identified, most of which were accepted by the leader. On a few occasions, members’ proposals were rejected, most of which were accompanied by the leader’s accountingAccounting, displaying his epistemic primacy and deontic reasoning. Through these accounts, the leaders seemed to simultaneously reassured the proposersProposal’ legitimacy and responsibility to contribute to joint decision makingJoint decision making as a shared practice observed in the trauma team interactions in the two distinctive sociocultural contexts. However, a difference in the team dynamics was foregrounded between the Japanese and the British teams; the deontic rightsDeontic right were given to a proposer in the former while they were distributed by the leader in the latter.