This research focuses on how research ethics committee and integrity board members discuss and decide on solutions to case scenarios that involve a dimension of research ethics or integrity in collaborative settings. The cases involved issues around authorship, conflict of interest, disregard of good scientific practice and ethics review, and research with vulnerable populations (children and neonates). The cases were set in a university, a hospital, or a research institute. In the research, we used a deductive qualitative approach with thematic analysis. Twenty-seven research ethics committee and research integrity board members from 16 European countries and one country outside Europe participated. Participants represented natural and life sciences, social sciences, and humanities. They worked on cases involving ethical/integrity issues in six different constellations. Results show that experts apply key elements of ethical decision making, namely identification of ethical issues, stakeholders, guidelines, solutions, and own positionality, in dealing collaboratively with ethics/ integrity problems, and the nature of the application depends on the complexity of the case. Understanding how individuals knowledgeable in research ethics and integrity, in this case, individuals serving on research ethics committees and integrity boards, approach ethical/ moral issues can help to identify strategies that may be useful in the development of research ethics and integrity training for junior researchers who may benefit from learning professional strategies.