Many Americans wonder about laws that are enacted but not enforced. For example, pirated DVDs, or digital versatile discs, are sold routinely on the streets and in the subways of New York City. Thousands of New Yorkers know this because they see it every day. Why don’t the police stop these illegal vendors of pirated merchandise?

The discs are spread on the floor of subway arcades, usually on a sheet. The vendor stands (or sits) at the site. When a customer makes a choice, sometimes by pointing to one of the titles displayed, the vendor gives it to him/her, at a price that is often $5. Bootlegged discs are often available within days after their initial release, and far before the time they are offered as DVDs.

The films are obviously not legitimately on sale; they are copied by camcorders operated surreptitiously at movie theatres or at preview screenings. Quality varies. Sometimes the films are indistinct, but try getting your money back. Of course, they are sold without regard for copyright law or any other requirement for the use of intellectual property. They are stolen goods. Many buyers know that, but are willing to risk poor quality, and support an illegal business in order to save money and see the movie sooner.

The question we ask is: How can these transactions, which are carried out openly, on a large sheet in a public place, go on without police collusion? We do not mean the commissioner, who is most unlikely to have received guidance from City Hall not to be concerned with this practice. We are also aware that the New York Police Department puts substantial resources in this area.

We believe that outright corruption is probably rare. The problem appears to be more in the apathy or inertia of some officers. Another possibility is that the officers may not have received instructions to patrol frequently the arcades and passageways where this activity is taking place.

We are not dealing with narcotics, which can be smuggled in people’s pockets, and where court warrants are required for certain searches. We describe a commodity that takes up a lot of space, and that is generally publicly displayed in order to be offered for sale. We also are dealing with a substantial repeat business for both buyers and sellers. Rule 16-J: Nobody does it once.

The people who sell these movies are not murderers, rapists, and robbers. Nor do they compel anyone to buy their goods. Nor does their merchandise poison or blind the buyers.

Why, then, be concerned? Are there not much greater evils in Metropolis, or even in Gotham? Do we have a burr over copies of movies? Does anyone care except the industry involved? Are they providing a service to low-income subway riders who otherwise could not afford to see recent movies? Are their children being deprived of wholesome entertainment in an effort to cater to the rapacity of Hollywood magnates? Why should the resources of the state be used to favor one set of businessmen over another? Aren’t there really more useful tasks for law enforcement?

We can’t swallow any of those propositions, beguiling as they may appear. The laws against theft are easy to understand, and they should be enforced. If they are not, what is to prevent the entire subway system from becoming a bazaar, making it difficult for riders to traverse the passageways.

What can we do about it? Here are some relatively simple suggestions.

1. Establish patrol routes for all large stations, with irregular hourly visits to passageways.

2. Upon contact with an illegal vendor, confiscate all the merchandise, and place it in a flexible but sealed container (it could be made of wire mesh).

3. Encourage riders to call 311 (not 911) to report vendors, and have such calls immediately transferred to the persons on patrol at the station that is named.

4. Require that every vendor be accurately identified at a police station, if his identity cannot be proven on the site.

5. Impose increasing penalties on multiple violators, leading to jail time for the third offense.

6. Find out where the movies were obtained, and go after the suppliers, the men (because they are all men) who are kingpins of the racket.

7. The question of what to do with the confiscated films is not easily resolved. There is a strong case for destroying them; one could also suggest giving them to charitable institutions. Recycling has its advocates in the environmental community, and might provide revenue to aid in the enforcement effort. Resale would put the city in the same business as the pirates.

We have discussed a simple example of a poorly enforced law. Consider the many more difficult enforcement issues: zoning, prostitution, zoning, narcotics, zoning, traffic offenses, safety laws, laws regulating personal conduct (some of which ought not to be enforced), as well as zoning (how many buildings are in violation of their certificates of occupancy?) And don’t forget the tax laws.

Law enforcement is more than the seven FBI index crimes, enumerated like the seven deadly sins and George Carlin’s seven dirty words. Seven may suggest sin and Satan to some, but no number should be surrendered to the fires of darkness, certainly not Mickey Mantle’s.

Mr. Stern is a former New York City parks commissioner and the director of New York Civic.