Unwritten Rule of Engineering #19: In all transactions be careful to “deal in” everyone who has a right to be in.
It is all too easy to overlook the interests of a department or individual who does not happen to be represented, or in mind, when a significant step is taken. Even when it does no apparent harm, most people do not like to be left out when they have a stake in the matter, and the effect upon morale may be serious.
Note particularly in this and the preceding rule the chief offense lies in the invasion of someone else’s territory without that person’s knowledge or consent. You may find it expedient on occasion to do parts of other people’s jobs in order to get your own work done, but you should first give them a fair chance to deliver on their own or else agree to have you take over. If you must offend in this respect, at least you should realize that you are being offensive.