Political aspects of IT projects

Implementation of a corporate IT system in most cases brings about drastic changes to the corporate political landscape and upsets the established balance of business unit interests. As a rule, attempts to modify this balance in a particular direction by force will fail as opposing parties will have enough means to succeed in resisting. Here the IT department plays a role that gives the most responsibility for the result and the least means of influence. How to help the IT Department to overcome lines of active or passive resistance?