How to Make Money Selling Drugs, an independent film due in theaters at the end of this month, makes a number of arguments for why we should end the war on drugs. A cop for 34 years, my reasons are simple: Drug prohibition is bad for public safety, and it's never going to work.

I worked the streets of Baltimore and its surrounding environs for most of my adult life. Anyone familiar with HBO's The Wire knows the complexities of what it means to be a cop in Baltimore, and how centrally the drug war figures into crime in the city.

Drug sales pay for the fancy cars and lavish lifestyles that create the aura of mystique around drug dealers. The film explores this mystique in depth: the potential to earn a lot while working relatively little is one that appeals to us all. For disadvantaged kids in the inner city, however, this potential means a great deal more than it does to the mostly middle class audience reading this article. It often means the only avenue of escape from a life of poverty.

For those kids, the dealers they see on the street are often the only materially successful people they know and identify with. Becoming a doctor or lawyer or other professional doesn't seem like a realistic career goal if you don't know anyone who's ever become one, if you don't go to a school colleges care about, if you don't have the money for college anyway. Drug dealers often fill the void left by the absence of these other role models.

Even if you feel little sympathy for those who eventually choose to sell drugs, there's an important reason for understanding this dynamic of limited life expectations. The logic of the drug war says that rather than focusing on users (the demand side of the equation), law enforcement should focus on the supply side -- limiting the amount of drugs that make it to the streets, so prices go up and people become less likely to pay. It sounds like good logic, except for one thing: no matter how much you try, because of the tremendous profits to be made, it's impossible to limit supply for very long.

Prosecuting individual drug suppliers is a lot like squeezing a water balloon: when you tighten in one place, another part of the balloon necessarily expands out. The police might arrest a dealer in one area of the city, but when they do, they create a vacuum in the market which others enthusiastically fill. Worse, the scramble to fill that void often leads to violent confrontations between groups competing for market share. This is one way in which drug prohibition not only fails to prevent violence, it actively generates it.

Here's another way: the White House Office of National Drug Control Policy estimates that Americans spend $65 billion a year on illegal drugs. Not only do we lose a lot of tax revenue and job creation opportunities because that money remains outside the legal market, all that money goes to criminals and criminal enterprises, who spend it on guns, sex trafficking, illegal gambling rings - pretty much every ill in America is funded by profits from drugs.

The fact that police and courts have to spend their time and resources prosecuting consensual crimes further undermines public safety. Police and police departments are often measured by the numbers of arrests they make each year. More arrests mean more promotions for the officers involved and, often, more federal grant money for the department. Guess which are easier to secure: drug arrests that can be made in minutes by going to the right area of town, or arrests for crimes that require careful investigation like rapes, burglaries,and murders? As police focus on drugs has intensified, the rate of murders police departments are able to solve has decreased dramatically across the country -- from 91 percent in 1963 to 61 percent in 2007.

And despite stated intentions to go after those at the top of organized crime rings, because of the use of informants and the tight control on information, it's much easier for crime bosses to snitch on those under them than the other way around. It's also much easier to pick up the corner boys selling on the streets than to conduct a thorough investigation that would net the more influential targets. This practice is also largely responsible for racial disparities in arrest rates. So low-level offenders, often people of color, get sent to jail where they are socialized into a culture of violence and, because of their conviction, become less likely to get a stable job, own a home, get financial aid for school. When they have kids, the cycle of limited life opportunities begins again.

Except for a few puffs of marijuana in high school, I've never ingested an illegal drug, nor do I intend to. Believe me, seeing firsthand the ravages of drug addiction is more effective a deterrent than any DARE program yet devised. However, just because something should be done about a problem doesn't mean that any answer will solve it. We cannot arrest our way out of this problem -- take it from someone who tried for 34 years.

Neill Franklin is the executive director of Law Enforcement Against Prohibition, a nonprofit representing more than 5,000 law enforcement officials opposed to the war on drugs, and a 34-year veteran of the Maryland state and Baltimore city police departments.

This post is part of a series produced by The Huffington Post to mark the theatrical and on-demand release of "How To Make Money Selling Drugs," a new documentary by Matthew Cooke that examines the drug trade from a variety of angles. For more info on the film, click here .