Jury has spoken in Martin case: Obama PRESIDENT Barack Obama has appealed for calm after an acquittal in the killing of black teenager Trayvon Martin, saying: "We are a nation of laws, and a jury has spoken." "I now ask every American to respect the call for calm reflection from two parents who lost their young son," he said in a statement the day after a jury found neighbourhood watchman George Zimmerman not guilty in a racially-charged trial. Obama, who had spoken emotively on the case before, noting that if he had a son he would have "looked like Trayvon Martin," reiterated that the impact of the death went much wider than the Florida town of Sanford. The death of Trayvon Martin was a tragedy. Not just for his family, or for any one community, but for America. I know this case has elicited strong passions. And in the wake of the verdict, I know those passions may be running even higher. He tied the killing of the teenager to the problems surrounding gun use in the US, an issue on which the president tried but failed to push through new control measures earlier this year. "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," Obama said. 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 honour Trayvon Martin. Zimmerman, 29, had been accused of pursuing Martin, 17, through a gated community in Sanford, and shooting him during an altercation on the rainy night of February 26, 2012. A six-woman jury late on Saturday acquitted Zimmerman, with spontaneous protests breaking out soon after in US cities including San Francisco, Philadelphia, Chicago, Washington and Atlanta.