The Department of Justice ("The Department") vigorously investigates and, where the evidence permits, prosecutes allegations of Constitutional violations by law enforcement officers. The Department's investigations most often involve alleged uses of excessive force, but also include sexual misconduct, theft, false arrest, and deliberate indifference to serious medical needs or a substantial risk of harm to a person in custody. These cases typically involve police officers, jailers, correctional officers, probation officers, prosecutors, judges, and other federal, state, or local law enforcement officials. The Department's authority extends to all law enforcement conduct, regardless of whether an officer is on or off duty, so long as he/she is acting, or claiming to act, in his/her official capacity.
In addition to Constitutional violations, the Department prosecutes law enforcement officers for related instances of obstruction of justice. This includes attempting to prevent a victim or witnesses from reporting the misconduct, lying to federal, state, or local officials during the course of an investigation into the potential misconduct, writing a false report to conceal misconduct, or fabricating evidence.
The principles of federal prosecution, set forth in the United States Attorneys' Manual ("USAM"), require federal prosecutors to meet two standards in order to seek an indictment.
First, the government must be convinced that the potential defendant committed a federal crime. Second, the government must also conclude that the government would be likely to prevail at trial, where the government must prove the charges beyond a reasonable doubt. See USAM § 9-27.220.
 The USAM provides only internal Department of Justice guidance. It is not intended to, does not, and may not be relied upon to create any rights, substantive or procedural, enforceable at law by any party in any matter civil or criminal. Nor are any limitations hereby placed on otherwise lawful litigative prerogatives of the Department of Justice.
The federal criminal statute that enforces Constitutional limits on conduct by law enforcement officers is 18 U.S.C. § 242. Section 242 provides in relevant part:
"Whoever, under color of any law, …willfully subjects any person…to the deprivation of any rights, privileges, or immunities secured or protected by the Constitution or laws of the United States [shall be guilty of a crime]."
Section 242 is intended to "protect all persons in the United States in their civil rights, and furnish the means of their vindication." Screws v. United States, 325 U.S. 91, 98 (1945) (quoting legislative history).
To prove a violation of § 242, the government must prove each of the following elements beyond a reasonable doubt: (1) that the defendant deprived a victim of a right protected by the Constitution or laws of the United States, (2) that the defendant acted willfully, and (3) that the defendant was acting under color of law. A violation of § 242 is a felony if one of the following conditions is met: the defendant used, attempted to use, or threatened to use a dangerous weapon, explosive or fire; the victim suffered bodily injury; the defendant's actions included attempted murder, kidnapping or attempted kidnapping, aggravated sexual abuse or attempted aggravated sexual abuse, or the crime resulted in death. Otherwise, the violation is a misdemeanor.
Establishing the intent behind a Constitutional violation requires proof beyond a reasonable doubt that the law enforcement officer knew what he/she was doing was wrong and against the law and decided to do it anyway. Therefore, even if the government can prove beyond a reasonable doubt that an individual's Constitutional right was violated, § 242 requires that the government prove that the law enforcement officer intended to engage in the unlawful conduct and that he/she did so knowing that it was wrong or unlawful. See Screws v. United States, 325 U.S. 91, 101-107 (1945). Mistake, fear, misperception, or even poor judgment does not constitute willful conduct prosecutable under the statute.
In cases of physical assault, such as allegations of excessive force by an officer, the underlying Constitutional right at issue depends on the custodial status of the victim. If the victim has just been arrested or detained, or if the victim is being held in jail but has not yet been convicted, the government must, in most cases, prove that that the law enforcement officer used more force than is reasonably necessary to arrest or gain control of the victim. This is an objective standard dependant on what a reasonable officer would do under the same circumstances. "The 'reasonableness' of a particular use of force must be judged from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight." Graham v. Connor, 490 U.S. 386, 396-97 (1989).
If the victim is a convicted prisoner, the government must show that the law enforcement officer used physical force to punish , retaliate against, an inmate, or otherwise cause harm to the prisoner, rather than to protect the officer or others from harm or to maintain order in the facility. See Whitley v. Albers, 475 U.S. 312, 319 (1986).
Law enforcement officers who engage in nonconsensual sexual contact with persons in their custody deprive those persons of liberty without due process of law, which includes the right to bodily integrity. The Department investigates and prosecutes instances of nonconsensual sexual misconduct committed by patrol officers, federal and state probation officers, wardens, and corrections officers, among others. Sexual misconduct includes, but is not limited to, sexual assault without consent (rape), sexual contact procured by force, threat of force or coercion, and unwanted or gratuitous sexual contact such as touching or groping.
To prove that a law enforcement officer violated a victim's right to bodily integrity, the government must prove that the victim did not consent to the defendant's actions. Prosecutors can establish lack of consent or submission by showing that the defendant officer used either force or coercion to overcome the victim's will. It is not necessary to prove that the defendant used actual violence against the victim. Coercion may exist if a victim is told that an officer will bring false charges or cause the victim to suffer unjust punishment.
Section 242 prohibits a law enforcement officer from acting with deliberate indifference to a substantial risk of harm to persons in custody. Therefore, an officer cannot deliberately ignore a serious medical condition of or risk of serious harm (such as a risk that an inmate will be assaulted by other inmates or officers) to a person in custody. To prove deliberate indifference, the government must prove that the victim faced a substantial risk of serious harm; that the officer had actual knowledge of the risk of harm; and that the officer failed to take reasonable measures to abate it.
An officer who purposefully allows a fellow officer to violate a victim's Constitutional rights may be prosecuted for failure to intervene to stop the Constitutional violation. To prosecute such an officer, the government must show that the defendant officer was aware of the Constitutional violation, had an opportunity to intervene, and chose not to do so. This charge is often appropriate for supervisory officers who observe uses of excessive force without stopping them, or who actively encourage uses of excessive force but do not directly participate in them.