English: A complaint system (also known as a conflict management system, internal conflict management system, integrated conflict management system dispute system) is a set of procedures used in organizations to address complaints and resolve disputes. Complaint systems in the US have undergone several innovations especially since about 1970 with the advent of extensive workplace regulation. Notably in many countries, conflict management channels and systems have evolved from a major focus on labor-management relations to a much wider purview that includes workers and also managers, non-union employees, professional staff, students, trainees, vendors, donors, customers, etc.

There is a substantial early history of scholarly work on and union and non-union procedures within organizations. This work focused primarily on based between union and non-union workers and their managers complain about services. Scholarly work has evolved to cover both a wider range of conflict management channels, and, also, a much wider range of disputants.In the 1970s and 1980s much interest arose in the United States, in dealing with conflict informally as well as formally, and in learning from conflict and managing conflict. In contemporary language, these discussions centered on the "interests" of all who would consider themselves stake-holders in a given conflict—and on systems change—as well as resolving grievances.

These discussions led to questions of how to think about complaint systems and how to link different conflict management offices and processes within an organization. Papers by Ronald Berenbeim, Mary Rowe, and Mary Rowe and Michael Baker, described a systems approach for dealing with complaints—and all kinds of disputes—within organizations.

Many authors extended the work of Berenbeim, Rowe, and Rowe and Baker, on the topic of internal complaint systems. They included: Douglas M. McCabe,William J. Ury, Jeanne M. Brett, and Stephen B. Goldberg(Ury, Brett and Goldberg in particular described conflict resolution within organizations in terms of interests, rights and power and the possibility of looping back from rights-based processes to interest-based solutions).Complaint_Department_please_take_a_number