The New York Times recently ran a story about New Dehli’s new Metro subway system. It offers a nice illustration of how a greenfield project creates an opportunity to establish new rules, particularly new informal rules enforced by norms.

Part of what people like about the new service is that the cars are clean and people are relatively courteous. Some riders are so pleased that they volunteer their time to ensure it stays that way. The volunteer monitors enforce rules like those against spitting and public urination. Though such rules are routinely ignored in the rest of the city, the volunteers appear to be successful in sustaining new norms of Metro riders.

Of course, New Dehli isn’t the only city struggling to establish norms of public hygeine. Even when cities enforce formal rules against things like spitting and public urination, creating a culture of compliance with the rules can be challenging. The Dehli Metro monitors bring to mind a unique group of like-minded enforcers in Paris, the Bad Behavior Brigade. The Brigade successfully suppresses a host of offenses, such as littering, failure to pick up after dogs, and unauthorized flyer distribution. Yet the offense of public urination remains a persistent problem despite the Brigade’s ticketing efforts and an increase in the number of public toilets in Paris.

As this example suggests, some norms are hard to change. When I traveled in France 30 years ago, the stenciled warning on walls said “Défense de Pisser.” Now the signs say “Défense D’Uriner.” At least the signs have become more polite even if the behavior has not.

If the problem persists, Paris might look elsewhere for effective enforcement strategies. As Ray Fisman and Edward Miguel point out in Economic Gangsters, the soft sanction of public ridicule offers one tack for establishing new norms and fostering compliance with the rules. They write about former Bogotá, Colombia mayor Antanas Mockus’s use of mimes to mock jaywalkers, reckless drivers, and other scofflaws. According to Fisman and Miguel, the mimes had a noticeable impact on the culture of compliance with traffic laws. The mayor reported that traffic fatalities fell by more than fifty percent between 1993 and 2003. Together with other programs, the mimes helped to reestablish the rule of law in post-Escobar Bogotá.

If mimes won’t keep people from using the walls of Paris as urinals, authorities may want to pursue a broader communications strategy to deal with the publicly unzipped. In When Brute Force Fails, Mark Kleiman describes New York City’s successful campaigns against fare-beating on the subways and squeegee men in the the streets. The experiences suggest that concentrated and well-publicized custodial arrests may be a relatively quick way to establish a lasting culture of compliance.

Kleiman describes the squeegee men as “something between aggressive beggars and low-grade extortionists.” Unprompted, squeegee men would clean the windshields of cars idling at lights and then ask to be paid. The experience for their “customers” ranged from mildly annoying to frightening. Turnstile jumping — riding the subway without paying the fare — was even more common than the squeegee scheme. In 1992, the Transit Authority estimated that nearly 176,000 people evaded subway fares each day. Like public urination, both turnstile-jumping and the squeegee racket were illegal but difficult to control and seemingly trivial compared to more serious crimes.

In both cases, the New York police department dramatically reduced violations by publicly announcing its intent to punish offenders and following-up with intensive arrests. In a relatively short period, the combination of public communication and concentrated enforcement led to low-violation equilibria without much need for serious follow-up enforcement. The credible threat of arrest made the squeegee scheme unprofitable and reestablished the norm of paying the fare among subway riders.

In dense urban settings, rules are essential for a high quality of life. In most cases, people behave well because the formal rules enforced by the state complement the informal rules that are embodied in norms and enforced by decentralized individual action. Because the conventional economic analysis of crime treats norms as exogenous, it may be missing much of the action on the front lines. Creative enforcement strategies — like those employed in Bogotá, New Dehli, and New York — don’t just change behavior. They change norms.

This post originally appeared on the NYU Stern Urbanization Project’s blog. To read the original post, click here.