Kyle Rittenhouse has been cleared of all charges after he fatally shot two men and wounded a third during the racial justice protests in Wisconsin last year.
A jury determined the 18-year-old had acted in self-defence and found him not guilty of two counts of homicide, one count of attempted homicide and two counts of recklessly endangering safety.
Rittenhouse’s defence team said the teen was a civil minded youngster who attended the protest in the city of Kenosha to protect private property.
The demonstration on August 25 had been marred by arson, rioting and looting.
Rittenhouse broke down sobbing after the verdict, which came shortly after the judge warned the courtroom to remain silent or be removed.
The teenager’s trial polarised America, highlighting gaping divisions in US society around contentious issues like gun rights.
Rittenhouse shot and killed Joseph Rosenbaum, 36, and Anthony Huber, 26, and fired a bullet that tore a chunk off the arm of Gaige Grosskreutz, 28.
In reaching their verdicts after more than three days of deliberations, the jury contended with duelling narratives from the defense and prosecution that offered vastly different portrayals of the teenager’s actions on the night of the shootings.
The defense argued that Rittenhouse had been repeatedly attacked and had shot the men in fear for his life.
The unrest followed the police shooting of a Black man named Jacob Blake, who was left paralysed from the waist down.
The prosecution portrayed Rittenhouse as a reckless vigilante who provoked the violent encounters and showed no remorse for the men he shot with his AR-15-style rifle.
Live-streamed and dissected by cable TV pundits daily, the trial unfolded during a time of social and political polarisation in the United States.
Gun rights are cherished by many Americans and are enshrined in the US Constitution even as the nation experiences a high rate of gun violence and the easy availability of firearms.
Rittenhouse, who testified that he had no choice but to open fire to protect himself, is viewed as a hero by some conservatives who favor expansive gun rights and consider the shootings justified.
Many on the left view Rittenhouse as a vigilante and an embodiment of an out-of-control American gun culture.
Protests against racism and police brutality turned violent in many US cities after the police killing of Black man George Floyd in Minneapolis three months before the Kenosha shootings.
The Rittenhouse verdict ended the highest-profile US civilian self-defence case since a man named George Zimmerman was acquitted in the fatal shooting of Trayvon Martin, an unarmed Black teenager, in Florida in 2013.