Explain how an \"interest group\" (or \"special interest group\") may try to influence public policy made by departments and/or agencies Solution Interest Groups Functions of interest groups Activities Structures Legitimacy Problems of analysis and research BIBLIOGRAPHY Interaction between the polity and organized interests has taken place in all periods of history. Estates, guilds, trading companies, and the like are the more immediate antecedents of the modern interest group, which may be defined as a voluntary association of individuals who band together for the defense of an .