The U.S. Department of Justice concluded that Arpaio oversaw the worst pattern of racial profiling in US history, and subsequently filed suit against him for unlawful discriminatory police conduct.

He served as a police officer in Las Vegas for six months before being appointed as a special agent with the Federal Bureau of Narcotics, which later became part of the Drug Enforcement Administration (DEA).

Those guidelines specify that a case can be cleared by exception only when a perpetrator's identity and location is known and there is sufficient evidence to support prosecution, but, due to special circumstances (such as the suspect dying, or extradition not being possible), an arrest cannot be made.

While providing police services for El Mirage, Arizona, the MCSO under Arpaio failed to follow through on at least 32 reported child molestations, even though the suspects were known in all but six cases.

[91] In October 2007, Mike Lacey and Jim Larkin, the founders and leaders of the Phoenix New Times, were arrested after publishing a news article on a grand jury investigation involving Arpaio's office.

[92] On the evening that the article was published, Lacey and Larkin were arrested by plainclothes sheriff's deputies, "handcuffed, put in dark SUVs with tinted windows and driven to jail.

[93] Lacey and Larkin filed a federal Section 1983 lawsuit for the violations of their civil rights, and in 2012 the U.S. Court of Appeals for the Ninth Circuit ruled that they could sue the Maricopa County Sheriff's Office for the arrests.

The panel found "clear and convincing evidence" that Thomas brought unfounded and malicious criminal and civil charges against political opponents, including four state judges and the Arizona Attorney General.

Arpaio's office kept a separate set of personnel books detailing actual work assignments, different from information kept in the county's official human resources records.

[113] The Republic also found that a restricted jail-enhancement fund was improperly used to pay for out-of-state training, a staff party at a local amusement park, and a $456,000 bus which Arpaio purchased in violation of county procurement rules.

The memo alleged that top officials in the MCSO "willfully and intentionally committed criminal acts by attempting to obstruct justice, tamper with witnesses, and destroy evidence.

Dowling later filed suit, alleging negligence, malicious prosecution, abuse of process and several constitutional violations, although Arpaio won summary judgment against her claims.

The plaintiffs were represented by the American Civil Liberties Union (ACLU), the Mexican-American Legal Defense and Education Fund (MALDEF), and the law firm of Covington & Burling.

[149] On May 24, 2013, Judge Snow issued a decision finding the policies and practices of Arpaio and his office discriminatory, in violation of the Fourth and Fourteenth Amendments and Title VI of the Civil Rights Act of 1964.

[150][151] In June 2013, the United States Department of Justice (DOJ) filed a Statement of Interest in the case, recommending the appointment of an "independent monitor to assess and report on MCSO's compliance with the remedial measures ordered by the Court.

The appeals court rejected this claim, upholding Judge Snow's inclusion of non-saturation patrols in his finding of racial profiling, and maintaining his rulings of corrective actions that included training and video recording of traffic stops.

[157] Two days after the hearing, having just been rebuked for mocking the court's order, Arpaio sent out a fundraising letter complaining of "Rampant UNFOUNDED [sic] charges of racism and racial profiling in my office.

[164][165] During a status conference on May 14, 2015, Judge Snow, reading from a prepared statement, said that documents unearthed from the "Seattle Operation" by the court-appointed monitor revealed "an attempt to construct a conspiracy involving this court" as well as other entities and individuals including the DOJ, former U.S. Attorney General Eric Holder, former Phoenix Mayor Phil Gordon, and former MCSO Executive Chief Brian Sands, among others.

[166] One week after this status conference, Arpaio's criminal defense attorney filed a motion to disqualify Judge Snow, claiming that he had moved from being an independent arbiter in the case into the role of investigating "issues involving his own family."

"[180] In 2012, after the judge assigned to the case "that the jury was to be told about the MCSO's coverup, including missing jail videos and recordings of Braillard's phone calls," the county settled the litigation for $3.25 million.

[189][128] On December 15, 2011, the Justice Department released their findings after a 3-year investigation of Arpaio's office amid complaints of racial profiling and a culture of bias at the agency's top level.

The report stated that under Arpaio, the Maricopa County Sheriff's Office has "a pervasive culture of discriminatory bias against Latinos" that "reaches the highest levels of the agency.

[193] The United States' claims in this suit encompassed, but were broader than, the unconstitutional discriminatory conduct that the Court in Melendres v. Arpaio found the MCSO to have engaged in concerning its immigration enforcement-related traffic stops.

[152] A DOJ representative said that the agency was left with no choice but to file suit after Arpaio's attorneys balked at a demand for a court-appointed monitor to ensure the sheriff's office complied with any settlement terms.

[198] At two press conferences held in March 2012, Arpaio and members of his Cold Case Posse claimed that President Barack Obama's long-form birth certificate, released by the White House on April 27, 2011,[199] is a computer-generated forgery.

[203] In response to Arpaio's claims, Joshua A. Wisch, a special assistant to the Attorney General of Hawaii, said in a statement, "President Obama was born in Honolulu, and his birth certificate is valid.

"[207] On December 15, 2016, Arpaio held a news conference along with posse member Mike Zullo, detailing "9 points of forgery" supposedly found on the digital image of Obama's birth certificate.

In a bid to shield Arpaio from criminal proceedings, his attorneys filed a written statement arguing that any mistakes in complying with the court's orders were unintentional, or the fault of former employees.

U.S. District Judge Susan Bolton wrote that Arpaio had "willfully violated an order of the court" by failing "to ensure his subordinates' compliance and by directing them to continue to detain persons for whom no criminal charges could be filed."

[240] On May 30, 2013, a recall attempt on Arpaio again failed only a week after a federal judge ruled that the sheriff's office had engaged in systematic discrimination against Latinos in violation of their constitutional rights.