The fatal shooting of Michael Brown, an 18-year-old African American, by a white police officer has sparked protests and outrage in the small town of Ferguson, Missouri. It has also touched off debates throughout the United States on racial harassment by the police and the increasing militarization of ordinary law enforcement after 9/11. Those conversations are important ones for Americans to have. Lost in the discussion, however, has been the role guns played in creating the environment of hostility between police and communities like Ferguson.

The problems of racial harassment and police militarization are exacerbated by the fact that America has a heavily-armed civilian population. While there are no official totals, there are an estimated 320 million guns in the United States, approximately one per person. It is often said that America has a gun culture, one that some celebrate and others bemoan. Whatever one's personal views about guns, there is no denying their presence in every American city, from Philadelphia to Ferguson. Nor should we fail to recognize the profound impact this has on law enforcement.

"The problems of racial harassment and police militarization are exacerbated by the fact that America has a heavily-armed civilian population."

Because there are so many guns out there, police officers are trained to live in fear of the very people they are supposed to protect and serve. Anytime a police officer pulls over a car, he or she must worry that the person inside that car will have a gun that could be turned on them. At training academies throughout the nation, new recruits are taught that cop-killers need two things: a will to kill and an opportunity to act. There's little an officer can do about will; anyone can have it without anyone else knowing. Officers can, however, limit the opportunities for a cop-killer to act by being prepared and quick to defend themselves.

In many police departments, the training involves the use of high-tech video simulations that put prospective officers in real-life situations where they'll have to decide whether to use force. A recruit will be shown a video of an encounter, shot from the point of view of the officer. In one, an officer will approach a vehicle pulled over for speeding when suddenly the driver pulls a gun and shoots. In another, an officer responding to a report of an armed robbery will enter a store when a potential suspect approaches and unexpectedly pulls what could be a gun out of his back pocket, only this time the gun is a wallet. The training is designed to prepare officers for a career on streets where a lot of people are armed and police have to make split-second decisions about the use of force. Police are trained, in other words, to be on edge.

The facts of the Brown shooting remain murky but the protests are motivated by a larger pattern: harassment of minorities by police. Communities of color know well that edgy cops and racial prejudice can be a dangerous brew. While inexcusable, racial stereotypes are predictably part of policing. Cops are taught to mistrust for self-protection, yet the vast majority of civilians they encounter are peaceful. It is little surprise that officers often fall back on racial or other stereotypes when faced with the difficult task of quickly determining who is a threat. Officers look for shortcuts to simplify high-pressure decisions. Such stereotypes are often misleading, reflecting the officer's biases especially in matters of race. They also endanger officers who lower their guard against people who don't fit the stereotypes and threaten civilians who do fit them.

"It is little surprise that officers often fall back on racial or other stereotypes when faced with the difficult task of quickly determining who is a threat."

The Brown protests have also set off a debate about militarization of the police since 9/11. That militarization is partially a result of our heavily-armed civilian population. The armored vehicles that have become the symbol of militarization are being purchased by law enforcement agencies to protect officers against gunfire. Police are equipping themselves with a variety of high-powered firearms because they feel outgunned by the criminals they have to defend themselves against. For some Americans, a high-powered weapon is just a fun toy to use at the gun range. For police officers, it is a threat that must be taken seriously.

As guns are part of the source of these law enforcement problems, no doubt some will suggest that gun regulation must also be part of the solution. Universal background checks, for example, can help keep guns out of the hands of those people who are more likely to threaten officers and other civilians. Restricting unusually high-powered weaponry reduces the need for the police to have even more powerful weapons for protection. Gun control, however, is no panacea and we should be realistic about what can be accomplished. This is not just a political question - whether the votes are there to support new laws - but a practical one. With so many guns already in circulation, police officers will not stop worrying about being shot and killed anytime soon.

Americans strongly support civilian gun ownership, and the right to keep and bear arms is guaranteed by the U.S. Constitution. There are some benefits to having this right, including the ability of people to defend themselves from criminals. Yet the shooting in Ferguson should also be cause to recognize how a heavily-armed civilian population adversely impacts policing and our communities.