As the murder rate continues to fall in the United States, Americans on Saturday night hung on the jury verdict of a Trayvon Martin case that's come to symbolize race and gun violence in America — the killing of a black teenager last February in Florida by a Hispanic neighborhood watchman carrying a concealed gun.

Twenty-nine-year-old George Zimmerman was found not guilty of second-degree murder or manslaughter for killing 17-year-old Trayvon Martin during an altercation in a gated community in Sanford, Fla. one rainy night. Although Zimmerman claimed common self-defense, the case highlighted "stand your ground" legal theory in America, which permits one to defend himself without any obligation to first retreat.

Florida in 2005 became the first of two dozen U.S. states to codify "Stand Your Ground," which is based in common law, into statute. Since then, the statute's impact on crime and violence has been hotly disputed by proponents and opponents, fueling the already fierce debate over gun control throughout the country.

Following the verdict, President Barack Obama, who early last year interjected himself into the debate, issued a statement calling for acceptance of the jury verdict but also reflection on gun violence.

"The death of Trayvon Martin was a tragedy. Not just for his family, or for any one community, but for America... We should ask ourselves if we're doing all we can to stem the tide of gun violence that claims too many lives across this country on a daily basis. We should ask ourselves, as individuals and as a society, how we can prevent future tragedies like this. As citizens, that's a job for all of us. That's the way to honor Trayvon Martin."

Most Gun Violence Occurs As Self-Defense

In January, Obama issues a series of executive orders including a directive to the U.S. Centers for Disease Control and Prevention (CDC) to study gun violence, a subject with a surprising dearth of scientific information.

Among study findings from CDC, researchers found that firearms accounted for "less than one percent of unintentional fatalities in 2010," and that mass shootings represent only a "small fraction of total firearm violence." But most surprisingly, the research showed that gun violence was less likely to occur during the commission of a crime than during an interpersonal altercation, when used as self-defense.

"Defensive uses of guns by crime victims is a common occurrence, although the exact number remains disputed," the CDC report said. "Almost all national survey estimates indicate that defensive gun uses by victims are at least as common as offensive uses by criminals, with estimates of annual uses ranging from about 500,000 to more than 3 million per year, in the context of about 300,000 violent crimes involving firearms in 2008."

Investigation Into "Stand Your Ground" Laws

While the CDC concluded that background checks and bans on types of firarms would not prevent such gun violence, the study did not discuss the impact of "stand your ground" laws.

In late May, a U.S. Commission on Civil Rights voted to investigate whether "stand your ground" laws have a racial bias, a dramatic undertaking requiring a lot of time and effort, that may be expedited by the current outrage over the Zimmerman trial verdict.

"We're going to take our own cut at it, go down, dig through records at the district attorney, police level and other things, and start going through ... to see whether or not, as some people suspect, that there is bias in the assertion or the denial of Stand Your Ground, depending on the race of the victim or the race of the person asserting the defense," said Democratic Commission Michael Yaki to the Huffington Post.

An investigation of the law's impact in Florida by the Tampa Bay Times dating from June 2012 found that defendants citing the "Stand Your Ground" law were more likely to be found not guilty if the victim was black. When a white victim was killed, 59 percent of defendants were found not guilty, compared to 73 percent of defendants who killed a black person.

Though Zimmerman did not use the "Stand Your Ground" defense, some violence experts (and prosecuting attorneys) would argue that the mere existence of the law in Florida could have compelled him to lower his threshold for violence.

"Our study finds that, that homicides go up by 7 to 9 percent in states that pass the laws, relative to states that didn't pass the laws over the same time period," said Mark Hoestra, an economist of Texas A&M University who investigated the impact of the laws. "We find that there are 500 to 700 more homicides per year across the 23 states as a result of the laws."

Civil And Federal Suits Still A Possibility

With Trayvon Martin's family and President Obama requesting that the public respect the jury's verdict, it's unclear where additional lawsuits may come from.

Although the Martin family has the option of pressing for a civil suit, in which monetary damages for emotional and physical harm are sought, the family has given no indication of whether they will pursue one.

On Sunday afternoon, the Department of Justice (DOJ) announced that the case is still under investigation as to whether or not Trayvon Martin's civil rights were violated, which are protected under federal law. A DOJ investigation on whether Martin was the target of racial profiling was opened last year, but was temporarily suspended as the state trial resumed.

Meanwhile, the National Association for the Advancement of Colored People (NAACP) has preemptively opened an online petition, which collected over 350,000 petitions and has since been taken down, urging the DOJ to press charges for civil rights charges, but not just for racial profiling.

"We will pursue civil rights charges with the Department of Justice, we will continue to fight for the removal of Stand Your Ground laws in every state, and we will not rest until racial profiling in all its forms is outlawed," said NAACP President Benjamin Jealous.

"The most fundamental of civil rights — the right to life — was violated the night George Zimmerman stalked and then took the life of Trayvon Martin," the petition read.