US government prosecutors investigating the fatal police shooting of a black teenager that sparked a Missouri city's nights of rage face an uphill fight delivering the swift or sweeping results demanded by rights activists.
St. Louis County Prosecuting Attorney Bob McCulloch expects a local grand jury investigating the killing to take evidence until mid-October, while a federal investigation may take longer and with results just as uncertain.
Protesters have called for the arrest of Officer Darren Wilson since the killing of Michael Brown, 18, in Ferguson on August 9. Defenders of the white officer say he acted lawfully to
defend himself during a confrontation with Brown.
US Attorney General Eric Holder answered calls for an independent investigation this week, putting some 40 FBI agents along with prosecutors in his Justice Department's Civil Rights
Division on the case despite the legal challenges.
What makes it difficult for the US Justice Department to prosecute local police for criminal civil rights violations, even when a death results, is the high bar of proving an officer's intent to violate civil rights.
Under laws in the United States, criminal charges of murder or manslaughter are most often left to the states, and federal criminal charges typically are brought against local law
enforcement as violations of people's civil rights.
"The government has to show that the police officer acted with specific intent to use more force than was reasonably necessary under the circumstances. You can't prosecute a police
officer for making a mistake or even for a lack of judgment," said William Yeomans, a former acting head of the Civil Rights Division.
"That can be particularly hard," he said. "They rarely set out to shoot someone."
Rodney king precedent
One of the Justice Department's more notable successes prosecuting law enforcement officers on criminal charges was perhaps also one of the most prominent cases of the last 25
years - the 1991 beating of Rodney King in Los Angeles.
After being acquitted by a state jury, two officers were convicted in federal court. Both were sentenced to 30 months. The two were criminally charged with deprivation of rights under
color of law and aiding and abetting that deprivation of rights. It was a rare success for federal prosecutors, although the legal proceedings lasted some five years. King died in 2012.
In another case, federal prosecutors obtained convictions against five New Orleans police officers for killings in the aftermath of Hurricane Katrina in 2005. The convictions were
thrown out last year because of prosecutorial misconduct, but a judge has ordered a new trial, now nine years since Katrina.
In 2011, federal prosecutors secured a conviction of a Spokane, Washington, police officer for a fatal beating five years earlier. The officer had pleaded not guilty. He was
sentenced to four years and three months in prison.
Legal experts say more often than not, federal prosecutions fall short. In 1999, four New York police officers fired 41 shots at unarmed African immigrant Amadou Diallo and killed him.
Local prosecutors charged the officers, who were white, with second-degree murder and other counts.
A jury acquitted them in 2000, and in January 2001 federal prosecutors declined to bring a case of their own, citing a lack of proof that the officers had specific intent to use
Federal prosecutors declined to bring charges also after New York police killed Sean Bell, an unarmed black man, on his wedding day in 2006. Since 2008, they have declined to charge police officers in other high-profile killings in California, Illinois, New York, Ohio and Washington state.
Demand for federal action
This time the pressures are greater on the Justice Department because of the nightly disturbances underscoring the community's racial tensions and because of demands from civil
rights leaders for federal government action. Now a fellow at American University, Yeomans predicted the federal government would stand aside if St. Louis County brought
a criminal case that validated the Justice Department's interest in civil rights and only act if the state seemed unable or unwilling to vindicate the civil-rights interest.
Robert Driscoll, a former deputy assistant attorney general in the Civil Rights Division, said that if it acts at all, the Justice Department would most likely bring a non-criminal civil
rights case, such as one about patterns of possible police violations of people's rights under the US Constitution.