[14][15][16][17] The US legal doctrine of qualified immunity has been widely criticized as "[having] become a nearly failsafe tool to let police brutality go unpunished and deny victims their constitutional rights," as summarized in a 2020 Reuters report.

In the late 19th and early 20th centuries, the Texas Rangers supported and participated in extrajudicial killings and lynch mobs, such as La Matanza (1910–1920) and Porvenir massacre (1918).

[42] The resulting "Report on Lawlessness in Law Enforcement" (1931) concluded that "[t]he third degree—that is, the use of physical brutality, or other forms of cruelty, to obtain involuntary confessions or admissions—is widespread.

[34] The Civil Rights Movement was the target of numerous incidents of police brutality in its struggle for justice and racial equality, notably during the Birmingham campaign of 1963–64 and during the Selma to Montgomery marches of 1965.

African-Americans and Latinos are disproportionately the targets of these raids,[60] and according to the ACLU, "Sending a heavily armed team of officers to perform 'normal' police work can dangerously escalate situations that need never have involved violence.

"[65] After the attacks of September 11, 2001, human rights observers raised concerns about increased police brutality in the U.S. An extensive report prepared for the United Nations Human Rights Committee, published in 2006, stated that in the U.S. the War on Terror "created a generalized climate of impunity for law enforcement officers, and contributed to the erosion of what few accountability mechanisms exist for civilian control over law enforcement agencies.

"[66] The culture of impunity for police is reinforced by law enforcement operations with the FBI's Joint Terrorism Task Force, which undertakes "disruption" actions against suspects instead of investigations and criminal charges.

However, the Pacifica Alliance to Stop Slavery and other advocates affirmed their knowledge of police brutality in this area and explained that the fear of retribution is the main deterrent for sex workers who seek to report offending officers.

"[71] Research shows that measures of the presence of black and Hispanic people and majority/minority income inequality are related positively to average annual civil rights criminal complaints.

[76][77] A 2015 study shows that racial biases in police departments are likely to occur in major metropolitan counties with greater levels of financial disparity, a higher percentage of Black population, and low median incomes.

[80][81] In a report published on January 5, 2021, Kenosha County District Attorney Michael Graveley declined to issue criminal charges against the three officers involved in the shooting, concluding that their "use of force… was justified, in keeping with Wisconsin Law, in keeping with the Kenosha Police Department's use of force training and policy, and widely accepted law enforcement use of force standards.

[84] Energy Transfer Partners (the pipeline company) also employed a private security firm who used attack dogs and pepper spray against water protectors who were attempting to defend sacred burial sites from being bulldozed.

[87] Enbridge (the pipeline company) enables increased police militarization by funding an escrow account that law enforcement uses to buy equipment and to train and pay officers.

Selwyn Raab of The New York Times wrote about how the "Blue Code of Silence among police officers helped to conceal even the most outrageous examples of misconduct.

[102] On 15 May 2020, Amnesty International suggested that American authorities should avoid repressive measures that unduly restrict human rights in the name of "protecting" people from COVID-19.

The videos verified by researchers and Amnesty's Crisis Evidence Lab claimed the use of detention as a first resort; excessive and unnecessary use of force in the enforcement of COVID-19 lockdowns; and the imposition of mandatory quarantines in inhumane conditions.

[103] On 22 June 2020, the University of Chicago reported that the police departments in the 20 largest American cities were failing to meet even the most basic international human rights standards governing the use of lethal force.

[104] Numerous doctrines, such as federalism, separation of powers, causation, deference, discretion, and burden of proof have been cited as partial explanations for the judiciaries' fragmented pursuit of police misconduct.

[108][109] The law of qualified immunity often shields police officers from prosecution, since it only permits lawsuits against government officials when they have violated a "clearly established" constitutional or statutory right.

Prosecutors tend to have a close working relationship with police officers, which creates another conflict of interest, and they are often reluctant to aggressively pursue cases against law enforcement.

[115] A study by the University of Chicago found that after deputies gained collective bargaining rights in Florida sheriff's offices incidents of violent misconduct increased by around 40%.

[124] The Blue Wall of Silence is ultimately held together by fear of exile, and when the police force is often treated as a "brotherhood", speaking against "brothers" gives a perceived reality of betrayal and infidelity.

The paper concluded that people with a higher fear of racial minorities and dehumanization had "a lower threshold for shooting Black relative to White and East Asian targets".

The department argued that it is typically an effort to ticket as many low-income black residents as possible in an attempt to raise local budget revenue through fines and court fees.

[198] According to a 2002 analysis, there is often a dramatic increase in unfavorable attitudes toward the police in the wake of highly publicized events such as the Rampart scandal in the late 1990s and the killings of Amadou Diallo (February 1999) and Patrick Dorismond (March 2000) in New York City.

[207] In May and June 2020, support for the Black Lives Matter movement surged among Americans as a result of the protests and unrest that broke out across the United States following the murder of George Floyd in Minneapolis.

[208] Democratic presidential nominee Joe Biden condemned police violence against African American communities and called for racial justice while speaking at George Floyd's funeral service.

[212] In a 1996 law journal article, it was argued that Judges often give police convicted of brutality light sentences on the grounds that they have already been punished by damage to their careers.

[220][18] Starting in around 2005, courts increasingly applied this doctrine to cases involving the use of excessive force, eventually leading to widespread criticism that it "has become a nearly failsafe tool to let police brutality go unpunished and deny victims their constitutional rights" (as summarized in a 2020 Reuters report).

[221][222] In July 2019, the Glimmerglass Festival in Cooperstown, New York, premiered Jeanine Tesori and Tazewell Thompson's opera Blue about African-American teenagers as an 'endangered species' often falling victim to police brutality.