There are two key problems with deterrence-based trust systems. First, they are expensive to develop and maintain (they require development,oversight, maintenance, and monitoring),and second, they can backfire. Reactance theory argues that people do not like their freedom taken away and will act to reassert it. For example, signs reading “Do not write on These Walls Under Any Circumstances” actually increase the incidence of vandalism (as compared to signs that say “Please Do Not Write on These Walls” or the complete absence of signs)