One of the three men came at Tayeh with a knife and held it to his neck. Tayeh swung his arm, the knife still in his hand. In the ensuing melee, Tayeh struck Tyrone in the torso. Then Tayeh jumped in his car and drove away. An officer picked him up 30 blocks away.

Grilled by investigators, then the district attorney, Tayeh said he had fought back in self-defense. He learned only after hours at the precinct that Gibbons had died. Tayeh was charged with second-degree murder. “No one understood how scared I was,” he recalls. Three years later, a jury accepted his self-defense argument and found him not guilty of manslaughter.

Tayeh was fortunate. While all 50 states have laws that protect the right of self-defense, this right appears nowhere in the U.S. Constitution. And the difficulty of applying the laws to specific places, circumstances and weapons has made such a defense a risky, and therefore rarely used, tactic in courts. Even more rare is a case in which a claim of self-defense leads to a not-guilty verdict.

Supremes weigh in
Last month, however, advocates of the self-defense argument received a boost from none other than the U.S. Supreme Court. Writing for the majority in a landmark ruling on gun rights, Justice Samuel Alito declared that self-defense is “a basic right, recognized by many legal systems from ancient times to the present.”

The 5-4 ruling, in McDonald v. City of Chicago, ruled unconstitutional Chicago’s 1982 ordinance prohibiting citizens from possessing handguns for private use, even in their homes. Since handguns are the weapons “most preferred” by citizens trying to defend themselves in their homes, banning handguns in the home fetters the right of self-defense, the court reasoned.

Though the Supreme Court’s ruling is unlikely to directly affect the laws of self defense, it lays the groundwork for subsequent lawsuits that seek to define, and likely widen, the laws of use and carry, says Ilya Shapiro, a senior fellow at the Cato Institute, a libertarian think tank based in Washington D.C.

These cases, Shapiro says, may in turn reshape the boundaries of the kind of force individuals can use to defend themselves.

“In evaluating future gun regulation, self-defense will be a very important part. That’s what the right to keep and bear arms is about,” says Shapiro. “It’s about protecting life, liberty, property. It will be up to the government to justify restrictions to those rights.”

But while the government sets the laws, it is law enforcement, prosecutors, judges and juries who ultimately decide when using force is justified, and when it is criminal.

That’s one reason the McDonald decision may not necessarily make it easier to litigate self-defense cases, argues Lisa J. Steele, a defense attorney who has written a brief on building a self-defense case for the National Association of Criminal Defense Lawyers. Such cases remain “a big gamble for the defendant,” she explains. “You’re saying, ‘I did this, I meant to do this, and I was justified in doing it.’” Those who choose to claim they killed in self-defense could walk out vindicated, or they could face decades in prison for manslaughter or murder.

Justifiable homicide
No one knows exactly how often Americans use guns or other weapons in self-defense. A 1995 phone survey by the U.S. Department of Justice estimated 1.5 million people may use guns in a defensive manner each year. The results were similar to a study done the previous year by Gary Kleck, a criminologist at Florida State University.

Only rarely does self-defense of any kind result in a homicide. The Federal Bureau of Investigation reported 245 “justifiable homicides” committed by civilians in the 14,180 murders recorded in 2008, the most recent year for which statistics are available. These numbers, reported by local law enforcement to the FBI, include only homicides that take place at the same time as a felony, like a store clerk who kills while a robbery is in progress, or a burglar who is shot while breaking into someone’s home.

The specificity of that category may leave hundreds of homicides committed in self-defense, like that in the case of Ziad Tayeh, uncounted. “There could be three times as many total defensive homicides as the FBI numbers show,” says Kleck, who researches crime and gun control. He bases his estimate on local studies with more detailed breakdowns of defensive homicides.

Few such self-defense homicides make it into court. Police dispatch straightforward cases early by not pressing charges. District attorneys and grand juries may filter other cases by choosing not to indict. This discretionary power makes it difficult to count how many self-defense cases arise each year. “It’s really the difficult, borderline cases that go to trial,” Kleck says.

Self-defense cases are also a trial of character. To decide whether the homicide was justified, a jury passes judgment not only on the defendant, who claims he was a victim, but also on the deceased, who the defense argues was in fact the aggressor.

Dangling in the wind
If the court or jury does not agree, notes defense attorney Steele, “you’re dangling in the wind.”

That’s where Andrew Hoeft-Edenfield, then a 20-year-old community college student, was left in May 2008 after a birthday party at an apartment just east of UC-Berkeley’s frat row ended in the fatal stabbing of Christopher Wootton, a 21-year-old Berkeley student weeks away from graduating with a degree in nuclear engineering.

At the trial, Hoeft-Edenfield’s lawyer, Yolanda Huang, argued it was a case of self-defense. She claimed that Wootton and a group of his frat brothers from Sigma Pi had ganged up on her client and his friend, outnumbering them in a fight. “It was in the dark, very late, in an enclosed area, and people were pummeling him,” Huang said, adding that Hoeft-Edenfield had pulled a knife in self-defense.

Prosecutor Connie Campbell painted it differently. She told the jury that Hoeft-Edenfield was into the “thug life,” charging that he had gone out looking for a fight that night. The trial centered on the characters of two young men: a UC-Berkeley star that the defense said had a history of violence versus a community college kid the prosecution said killed intentionally and without remorse.

On May 13, 2010, Hoeft-Edenfield was found guilty of second-degree murder. He has been sentenced to 16 years to life and is currently being held at San Quentin Reception Center just outside San Francisco. His attorney says he will appeal.

Not surprisingly, his family feels he was given a bum rap. “I feel like my son was really defending himself,” said Ellen Hoeft-Edenfield, 62, who points out that her son and his friend were outnumbered three to one. “He was put in a situation where he really didn’t have any other choice.”

But Wootton’s fraternity brother Ryan Rudnitsky, 24, disagrees, “What do you have a knife for?” he wonders. “In some small inkling way, [Hoeft-Edenfield] had intention to use it.”

Stand your ground
Had Hoeft-Edenfield been tried in Florida, things might have turned out differently. While the right of self-defense is fairly standard across the states, some recent laws offer individuals the right to use force more freely both inside and outside the home.

In order to use force in any state, the threat to life or limb must be imminent. There must be no other choice but to resort to using force. That force, when used, can be no more than absolutely necessary.

The law seems simple, but each facet presents hard questions. How imminent was that danger? What is necessary force? Was there really no other choice but violence?

Self-defense laws have always allowed people to “meet force with force” if confronted with danger in their home. Many jurisdictions once had a “duty to retreat” clause for incidents outside the home; it required those who faced danger to try to get out of the situation before resorting to violence.

In 2005, a Florida law eliminated the “duty to retreat,” allowing Floridians to “meet force with force” anywhere they had a “legal right to be.” Unlike California, which also has no duty to retreat, Floridians may use lethal force in and outside their homes. Thirty states now have “stand your ground” legislation that eliminates to the duty to retreat.

The legislation has been supported by the National Rifle Association and other gun-rights activists who advocate for broader Second Amendment rights, often basing their arguments on the doctrine of self-defense.

“I see it as kind of a moral victory for the people who defend themselves,” says Massad Ayoob, a police captain in New Hampshire who has worked as a firearms trainer for police and civilians. To Ayoob, the right to bear arms, including guns, “brings parity” to life-threatening situations.

“If the criminal has a gun and the victim does not, that’s about as bad as it can get,” he says.

But Ayoob also admits that the race, class or circumstances in which the victim finds himself may effect the outcome of a self-defense claim in court. He pointed to the case of Ronnie Barlow, a young black man from Arizona who was in 1990 convicted of second-degree murder for what he said was a self-defense shooting. He said he was attacked by 21-year-old Robert Lockwood, a white man with a long criminal history and the son of a local judge, but the jury didn’t buy it. The judge, however, saw it differently and reduced the jury verdict to manslaughter. Two years later, Barlow was released.

Race and self-defense
In legal circles, one of the most talked-about components of the McDonald case was Justice Clarence Thomas’ opinion. While he voted with the majority, he offered a controversial 56-page interpretation that framed Second Amendment protection in terms of racial history.

In the Reconstruction era following the Civil War, black citizens in the South “were tortured and killed for a wide array of alleged crimes, without even the slightest hint of due process,” Thomas wrote. “The use of firearms for self-defense was often the only way black citizens could protect themselves from mob violence.”

The argument led to comparisons to Malcolm X in the Washington Post, and a general sense that the opinion was, legally and rhetorically, a bold step for the oft-silent justice. But it also implied that while the right to self-defense is “ancient,” our perceptions of the proper use of force in self-defense can be a product of our historical moment.

To defense attorney Steele, there’s no question about that. “There’s class issues built into this. There’s race issues built into this. It gets really complicated really quickly,” she says.

That’s because there’s a tricky question at the heart of any determination of self-defense: What would a reasonable person have done?

The “reasonable man” — or, now, “reasonable person” — doctrine is the cornerstone of a self-defense case, explains Cynthia Lee, a law professor at George Washington University. Juries must decide if the sequence of events was reasonable not only in the defendant’s mind but also from an outside perspective.

“The reasonableness requirement is imposed to lend an air of objectivity to the defense,” says Lee, the author of “Murder and the Reasonable Man,” a study of how beliefs and social norms play out in criminal cases, including self-defense trials.

“The problem is of course that reasonableness is in the eye of the beholder,” she says. “What’s reasonable to one person is not reasonable to another.”

In recent years, the courts and state legislatures have opened up more room for questions about what constitutes an “imminent” threat and whether a reasonable person must try to flee before using force.

Increased legal acceptance of the “battered person’s syndrome” in the early 1990s allowed juries to hear how an abused person — often, a woman — might feel she had no choice but to kill to save her life. This challenged the long-standing notion that the threat to one’s life had to be imminent. A battered person may, some believe, kill because the abuse is perceived to be life-threatening even if it isn’t happening right then.

Like “stand your ground laws,” battered-person defenses show that societal views can come into play in the long-standing right to self-defense, but nothing may indicate that better than the juries themselves.

Self-defense cases offer juries a lot of leeway to decide what they believe is reasonable and just, regardless of the law. “What the law on the books requires and what happens in action may be two different things,” Lee says. “Prosecutors, cops, jury members. We’re all people — and stereotypes about certain groups affect us all.”

The McDonald decision means that courts throughout the country will grapple for years with interpretations of the Second Amendment and the right of self-defense. But when the cases make it in to court, justice may depend less on the letter of state law than on the state of mind of the 12 people seated in that jury box.

For more information and news about gun rights and courts, please check out The Crime Report.