
Defensive gun use (DGU) is the use or presentation of a firearm for self-defense, defense of others or in some cases, protecting property. The frequency of incidents involving DGU, and their effectiveness in providing safety and reducing crime is a controversial issue in gun politics and criminology, chiefly in the United States. Different authors and studies employ different criteria for what constitutes a defensive gun use which leads to controversy in comparing statistical results. Perceptions of defensive gun use are recurring themes in discussions over gun rights, gun control, armed police, open and concealed carry of firearms.

On August 9, 2014, Michael Brown Jr., an 18-year-old black man, was fatally shot by 28-year-old white Ferguson police officer Darren Wilson in the city of Ferguson, Missouri, a suburb of St. Louis. Brown was accompanied by his 22-year-old friend Dorian Johnson. Wilson said that an altercation ensued when Brown attacked Wilson in his police vehicle for control of Wilson's gun until it was fired. Johnson said that Wilson initiated a confrontation by grabbing Brown by the neck through his car window, threatening him and then shooting at him. At this point, both Wilson and Johnson state that Brown and Johnson fled, with Wilson pursuing Brown shortly thereafter. Wilson stated that Brown stopped and charged him after a short pursuit. Johnson contradicted this account, stating that Brown turned around with his hands raised after Wilson shot at his back. According to Johnson, Wilson then shot Brown multiple times until Brown fell to the ground. In the entire altercation, Wilson fired a total of twelve bullets, including twice during the struggle in the car; the last was probably the fatal shot. Brown was struck six times, all in the front of his body.

On December 11, 2012, a shooting occurred at the Clackamas Town Center in the relatively urban section of Clackamas County, just outside the city of Portland, Oregon, United States. The gunman, 22-year-old Jacob Tyler Roberts, ran into the shopping center wearing black clothing and a "Jason Vorhees" mask and sporadically opened fire using a Stag Arms AR-15 rifle stolen from a friend. He fired a total of 17 shots, killing two people and seriously wounding a third. Many shots were ricochets. Having attempted to reload his weapon and dropping three magazines, Roberts entered an employee only back stairwell that runs behind all stores in the mall and committed suicide after descending one level. He had no connection to any of his victims, and it was believed to be a senseless and random act of violence. The Clackamas Town Center has a posted policy of prohibiting any firearms on the premises.

The Curtis Culwell Center attack was a failed terrorist attack on an exhibit featuring cartoon images of Muhammad at the Curtis Culwell Center in Garland, Texas on May 3, 2015, which ended in a shootout with police guarding the event, and the deaths of the two perpetrators. The attackers shot an unarmed Garland Independent School District (GISD) security officer in the ankle. Shortly after opening fire, both attackers were shot and killed by an off-duty Garland police officer.

Deadly force, also known as lethal force, is the use of force that is likely to cause serious bodily injury or death to another person. In most jurisdictions, the use of deadly force is justified only under conditions of extreme necessity as a last resort, when all lesser means have failed or cannot reasonably be employed.

Yoshihiro Hattori was a Japanese student on an exchange program to the United States who was shot to death in Baton Rouge, Louisiana. He was on his way to a Halloween party and went to the wrong house by mistake. Property owner Rodney Peairs fatally shot Hattori, thinking that he was trespassing with criminal intent. The shooting and Peairs' acquittal in the state court of Louisiana received worldwide attention.

Vanessa Rosalia Marquez was an American actress. She was primarily known for her recurring role in the first three seasons of ER as nurse Wendy Goldman, as well as her role as Ana Delgado in the 1988 biographical drama film, Stand and Deliver.

The shooting of Antonio Martin occurred on December 23, 2014, in Berkeley, Missouri, a suburb of St. Louis. Martin, an 18-year-old black male, was fatally shot by a white Berkeley police officer when Martin pulled a gun on him. The shooting sparked protests in the St. Louis area and other cities in the U.S. The shooting elicited comparison to the earlier shooting death of Michael Brown two miles away in Ferguson, Missouri.

Luciano Re Cecconi was an Italian footballer, who played as a midfielder; a fast, strong, athletic, and hardworking player, known for his speed, tenacity, and stamina, he functioned as a box-to-box midfielder or as a defensive or central midfielder for his teams. He was also known for his sense of humour throughout his career; and was nicknamed l'Angelo Biondo, for the colour of his hair.

On November 22, 2014, Tamir E. Rice, a 12-year-old African-American boy, was killed in Cleveland, Ohio, by Timothy Loehmann, a 26-year-old white police officer. Rice was carrying a replica toy gun; Loehmann shot him almost immediately after arriving on the scene. Two officers, Loehmann and 46-year-old Frank Garmback, were responding to a police dispatch call regarding a male who had a gun. A caller reported that a male was pointing "a pistol" at random people at the Cudell Recreation Center, a park in the City of Cleveland's Public Works Department. At the beginning of the call and again in the middle, he says of the pistol "it's probably fake." Toward the end of the two-minute call, the caller states that "he is probably a juvenile", but this information was not relayed to officers Loehmann and Garmback on the initial dispatch.

Odell Waller was an African-American sharecropper from Gretna, Virginia, executed for the fatal shooting of his white landlord, Oscar Wheldon Davis, on July 15, 1940. Waller unsuccessfully maintained at his trial that the killing had been in self-defense, but was convicted by a jury of white citizens who had paid the poll tax, a measure that effectively barred blacks and poor whites from jury service.