special interest

is a problem that can only be prevented by competition because it is human nature to try to get this favor.

If we have system in which government is in a position to give large favor it's human nature to try to get this favor whether those people are large enterprises, or whether they're small businesses like farmers, or whether they're representatives of any other special group. The only way to prevent that is to force them to engage in competition one with the other. Milton Friedman

special interest, n.Definitions

special interest