Columbine effect

The Columbine effect is the legacy and impact of the 1999 Columbine High School massacre. The shooting has inspired numerous copycat crimes, with many killers taking their inspiration from Eric Harris and Dylan Klebold, describing the two perpetrators as being martyrs. The shooting has also had a significant impact on popular culture.
Background.
On April 20, 1999, Columbine High School seniors, Eric Harris and Dylan Klebold, murdered 12 students and one teacher then injured 24 others. Around 50 minutes after the shooting began, Harris and Klebold took their own lives in the library, where the majority of their victims died. It was at the time, the deadliest shooting at a high school in American history. The shooting was the most covered news story of 1999, and third most followed by the American public of the entire decade.
Effects on schools.
Following the Columbine shooting, schools across the United States instituted new security measures such as transparent backpacks, metal detectors, school uniforms, and security guards. Some schools implemented the numbering of school doors to improve public safety response. Several schools throughout the country resorted to requiring students to wear computer-generated IDs.
Schools also adopted a zero tolerance approach to possession of weapons and threatening behavior by students.
Despite the effort, several social science experts feel the zero tolerance approach adopted in schools has been implemented too harshly, with unintended consequences creating other problems. Despite the safety measures that were implemented in the wake of the tragedy at Columbine, school shootings continued to take place in the United States at an alarming rate. Virginia Tech, Sandy Hook, and Stoneman Douglas were three subsequent school shootings that far surpassed the casualties of the 1999 massacre, subsequently raising concern of gun violence in the United States.
Some schools renewed existing anti-bullying policies. Rachel's Challenge was started by victim Rachel Scott's parents, and lectures schools about bullying and suicide.
Police tactics.
Police departments reassessed their tactics and now train for Columbine-like situations after criticism over the slow response and progress of the SWAT teams during the shooting. Sheriff Stone did not seek reelection.
Police followed a traditional tactic at Columbine: surround the building, set up a perimeter, and contain the damage. That approach has been replaced by a tactic known as the Immediate Action Rapid Deployment tactic. This tactic calls for a four-person team to advance into the site of any ongoing shooting, optimally a diamond-shaped wedge, but even with just a single officer if more are not available. Police officers using this tactic are trained to move toward the sound of gunfire and neutralize the shooter as quickly as possible. Their goal is to stop the shooter at all costs; they are to walk past wounded victims, as the aim is to prevent the shooter from killing or wounding more. Dave Cullen has stated: "The active protocol has proved successful at numerous shootings...At Virginia Tech alone, it probably saved dozens of lives."
Influence on other shootings.
The Columbine shootings influenced subsequent school shootings, with several such plots mentioning it. Fear of copycats has sometimes led to the closing of entire school districts. According to psychiatrist E. Fuller Torrey of the Treatment Advocacy Center, a legacy of the Columbine shootings is its "allure to disaffected youth." Ralph Larkin examined twelve major school shootings in the US in the following eight years and found that in eight of those, "the shooters made explicit reference to Harris and Klebold." Larkin wrote that the Columbine massacre established a "script" for shootings. "Numerous post-Columbine rampage shooters referred directly to Columbine as their inspiration; others attempted to supersede the Columbine shootings in body count.
A 2015 investigation by CNN identified "more than 40 people...charged with Columbine-style plots." A 2014 investigation by ABC News identified "at least 17 attacks and another 36 alleged plots or serious threats against schools since the assault on Columbine High School that can be tied to the 1999 massacre." Ties identified by ABC News included online research by the perpetrators into the Columbine shooting, clipping news coverage and images of Columbine, explicit statements of admiration of Harris and Klebold, such as writings in journals and on social media, in video posts, and in police interviews, timing planned to an anniversary of Columbine, plans to exceed the Columbine victim counts, and other ties.
In 2015, journalist Malcolm Gladwell writing in "The New Yorker" magazine proposed a threshold model of school shootings in which Harris and Klebold were the triggering actors in "a slow-motion, ever-evolving riot, in which each new participant's action makes sense in reaction to and in combination with those who came before."
FBI former profiler Mary Ellen O'Toole said on CNN during the 20th anniversary of the massacre in 2019, and during the chase of Florida teenager Sol Pais, that she opposed the release of the Basement Tapes because of the call made by Eric Harris to other would-be shooters to "join him in infamy". She also highlighted that it was most likely males to be obsessed by the shooting and that the case of Sol Pais was rare due to her being a female.
Copycats.
The first copycat may have been the W. R. Myers High School shooting, just eight days after Columbine, when a 14-year-old Canadian student went into his school at lunchtime with a sawed-off .22 rifle under his dark blue trench coat, and opened fire, killing one student. A month after the massacre, Heritage High School in Conyers, Georgia had a shooting which Attorney General Janet Reno called a Columbine "copycat". A friend of Harris and Klebold, Eric Veik, was arrested after threatening to "finish the job" at CHS in October 1999.
In 2001, Charles Andrew Williams, the Santana High School shooter, reportedly told his friends that he was going to "pull a Columbine," though none of them took him seriously. In 2005, Jeff Weise, an American Indian who wore a trench coat, killed his grandfather, who was a police officer, and his girlfriend. He took his grandfather's weapon and his squad car, and drove to his former high school in Red Lake and murdered several students before killing himself. In an apparent reference to Columbine, he asked one student if they believed in God.
The perpetrator of the Dawson College shooting wrote a note praising Harris and Klebold. Convicted students Brian Draper and Torey Adamcik of Pocatello High School in Idaho, who murdered their classmate Cassie Jo Stoddart, mentioned Harris and Klebold in their homemade videos, and were reportedly planning a "Columbine-like" shooting. The perpetrator of the Emsdetten school shooting praised Harris in his diary.
In November 2007, Pekka-Eric Auvinen imitated Columbine with a shooting in Jokela in Tuusula, Finland. Prior to the shooting, he had used the nickname "NaturalSelector89" online, was interested in American school shootings, and wore a shirt which said "Humanity is Overrated".
In December 2007, a man killed two at a Youth with a Mission center in Arvada, Colorado and another two at the New Life Church in Colorado Springs before killing himself. He quoted Harris prior to the attack under the heading "Christianity is YOUR Columbine".
In a self-made video recording sent to the news media by Seung-Hui Cho prior to his committing the Virginia Tech shootings, he referred to the Columbine massacre as an apparent motivation. In the recording, he wore a backwards baseball cap and 
referred to Harris and Klebold as "martyrs." Adam Lanza, the perpetrator of the Sandy Hook Elementary School shooting, had "an obsession with mass murders, in particular, the April 1999 shootings at Columbine High School in Colorado."
In 2011 Tristan van der Vlis shot and killed six people in a shopping mall in Alphen aan den Rijn in the Netherlands before committing suicide. He was obsessed with the Columbine shootings. The date he chose for his attack was April 9, which was the birthday of Eric Harris, and he started shooting at 12:08 pm, the time when Harris committed suicide.
The Tumblr fandom gained widespread media attention in February 2015 after three of its members conspired to commit a mass shooting at a Halifax mall on Valentine's Day. In 2017, two 15-year-old school boys from Northallerton in England were charged with conspiracy to murder after becoming infatuated with the crime and "hero-worshipping" Harris and Klebold.
The Santa Fe High School shooting, in which ten people were killed, strongly resembled the Columbine massacre; the perpetrator, Dimitrios Pagourtzis, used a pump-action shotgun and homemade explosives, wore similar clothing as Harris and Klebold (including a black trench coat and combat boots) and reportedly yelled "Surprise!" to a victim during the shooting, a possible reference to the library massacre at Columbine. The Kerch Polytechnic College massacre appears to be a copycat crime. The shooter wore a white shirt which said "Hatred" (in Russian), one fingerless glove, planted bombs, and committed suicide with a shotgun in the library, all very similar to Harris' outfit and suicide.
In popular culture.
"Columbine" has since become a euphemism for a school shooting, rather like "going postal". A video game called "Super Columbine Massacre RPG!" was based on the massacre.
The 2016 biographical film "I'm Not Ashamed", based on the journals of Rachel Scott, includes glimpses of Harris's and Klebold's lives and interactions with other students at CHS. The 1999 black comedy, "Duck! The Carbine High Massacre" is inspired by the Columbine massacre. The 2003 Gus Van Sant film "Elephant" depicts a fictional school shooting, but is based in part on the Columbine massacre. The 2003 Ben Coccio film "Zero Day" was also based on the massacre.
The first documentary on the massacre may have been the TLC documentary "Lost Boys" in 2000. The 2002 Michael Moore documentary film "Bowling for Columbine" won several awards. Also in 2002, A&E made "Columbine: Understanding Why".
Rapper Eminem references the shooting multiple times throughout his discography. Most famously, "I'm Back" off of "The Marshall Mathers LP" (2000) contained a line about Columbine that was censored. He references this censorship in "Rap God" ("The Marshall Mathers LP 2", 2013) and repeats the line, saying it will not be censored this time because he was not as famous as when "I'm Back" was released.
Fred Durst references the Columbine shooting in the Limp Bizkit song "Head for the Barricade", which is on the 2003 album "Results May Vary", and the reference wasn't censored on the explicit or edited versions of the album.
In 2004, the shooting was dramatized in the documentary "Zero Hour". In 2007, the massacre was documented in an episode of the National Geographic Channel documentary series "The Final Report".
The 2009 film "April Showers", which was written and directed by Andrew Robinson, who was a senior at CHS during the shooting, was based on Columbine. The 2013 film "Kids for Cash" about the kids for cash scandal detail it as part of the "zero-tolerance" policy in the wake of the Columbine shootings.
Columbine students Jonathan and Stephen Cohen wrote a song called "Friend of Mine (Columbine)", which briefly received airplay in the US after being performed at a memorial service broadcast on nationwide television. The song was pressed to CD, with the proceeds benefiting families affected by the massacre, and over 10,000 copies were ordered. Shortly following the release of the CD single, the song was also featured on the "Lullaby for Columbine" CD.
Since the advent of online social media, a fandom for shooters Harris and Klebold has had a documented presence on social media sites, especially Tumblr. Fans of Harris and Klebold refer to themselves as "Columbiners." An article published in 2015 in the "Journal of Transformative Works", a scholarly journal which focuses on the sociology of fandoms, noted that Columbiners were not fundamentally functionally different from more mainstream fandoms. Columbiners create fan art and fan fiction, and have a scholarly interest in the shooting.