"We pulled rank"

To pull rank means to make something happen or to override a decision made by others, based solely on the fact that you are in a position with greater authority. For example, when a group of army officers gets together and wants to decide where to go for lunch, all the lieutenants can say "let's go to restaurant X"; but the captain can pull rank and say "no, we're going to Y because I want to."

It generally has a negative connotation that someone is doing something because it appeals to them personally, rather than because the decision makes logical sense within whatever bureaucratic structure has granted them authority; often the decision may fly in the face of the greater good.

The New Oxford American Dictionary says:

pull rank: take unfair advantage of one's seniority or privileged position.

The “unfair” connotation is not always very strong, however, and to explain it in my own words, I would say “use one’s hierarchical rank to assert one's authority”.