Many of the names are probably familiar: Trayvon Martin, Michael Brown, Eric Garner, Oscar Grant, Akai Gurley, Jordan Davis, Tamir Rice, Sean Bell and now Walter Scott. Others may not be: Belinte Chee, John Williams, Renisha McBride, Rumain Brisbon, Cesar Arce, DeMarcus Carter, Jessica Hernandez, Charley Leundeu "Africa" Keunang, D'Andre Berghardt, Jr., Gabriella Nevarez, John Crawford III, and scores of others.

All are unarmed black or brown victims killed by people claiming self-defense. Some were killed by police; others by civilians. In all but three of the resolved cases, the killer was either not charged or was acquitted in the homicide. As a matter of law, the killings were labeled justifiable.

Is this the story, as some argue, of the law vindicating the claims of individuals who rightly reacted out of fear? Or is it of institutionalized racist violence? In the public discourse, it often comes down to a debate about whether or not each case was "about race." But that is asking the wrong question. The question is not whether race mattered in each case, but how it did and how the law should respond.

Stranger self-defense cases (whether by police or by civilians) are always about race. In fact, it is impossible to take race out of self-defense law. This is because self-defense involves a split-second assessment of whether a stranger is about to kill you. We can rely only on easy-to-see cues to make that determination. Race is an irrevocable part of that mix of cues. We can't close our eyes and not see it. Race can also influence our best guesses about other factors -- what we think someone is doing, whether we think we see a weapon, whether the person looks out of place. All of that is colored by race.

Of course in self-defense law, the fear has to be reasonable. This is where law is supposed to operate as a check against irrational people, like racist vigilantes. But race matters at the objective level too because we all share a certain level of bias. As a baseline assumption, we tend to think black and brown men are probably up to no good, just like we tend to think white women are probably not a threat.

For example, social psychologists Jennifer Eberhart, Phillip Atiba Goff, Valerie Purdie-Vaughns, and Paul Davies have found that "[m]erely thinking about blacks can lead people to evaluate ambiguous behavior as aggressive, to miscategorize harmless objects as weapons, or to shoot quickly, and, at times, inappropriately." When psychologist B. Keith Payne's research subjects were shown photos of a person and then asked to make a snap judgment about the identity of an object, they were more likely to mistakenly think the object was a gun if they saw an image of black person. Other similar studies have confirmed this "shooter bias" or "weapons bias."

Because these implicit biases are widely held, a cop, judge, or jury member is more likely to be able to sympathize with fear of a black or brown person and to view the killing as justifiable. Under the law of self-defense, a person's fear doesn't have to be correct to justify deadly force; it just has to be reasonable.

This inevitable potential for bias should make us cautious. It should make us want to carefully restrict when self-defense can be claimed and require a lot of evidence to support it. Instead, most states are expanding self-defense, passing new laws to make it available in more circumstances and make it easier to prove. Even the traditional version of self-defense law is broader than many assume. In most states, it is legal to kill a person who is breaking into your home, even if you are not in fear for your life. It is also legal in many states to kill to stop any forcible felony, not just a deadly assault. It is usually legal for police to kill to stop a fleeing felon who poses a danger to others.

More recent laws expand the doctrine even further. The most widely known version of this is the "Stand Your Ground" law, which allows you to kill without retreating from a conflict, even if you could have escaped danger by walking away. Other provisions extend the right of self- and home-defense to more places, making it legal to kill someone (without retreating) who threatens you in your workplace or is trying to break into an unoccupied car or boat. Some states are considering laws that would eliminate the "reasonableness" requirement, making a killing justifiable as long as it is based on an honest fear, however unreasonable that fear might be.

Social scientists have demonstrated that race affects our perceptions of dangerousness, our experience of fear, and our response to it. Yet, the law does not recognize racism as a problem unless it comes in the form of hateful, discriminatory statements like the emails sent by police and court staff in Ferguson, Missouri. Unless intentionally racist action is the only plausible explanation a specific incident, the legal system tends to respond by burying discussion of race. This is what happened when attorneys in the Zimmerman trial were barred from using the term "racial profiling." A more nuanced appreciation of the relationship between race and fear is needed to understand the way race matters -- and it always does -- in self-defense cases.