First formed on September 24, 1789, with the federal judiciary under George Washington's presidency, the Marshals were empowered to be the federal government's civilian law enforcement arm.  Washington himself appointed the first men to hold this position.  Their duties involved supporting and protecting federal judges and carrying out the laws that the judges, the President, or Congress handed down.  They served subpoenas, warrants, and other process papers issued by the courts.  They also made the arrests and handled the prisoners. These functions involved them in some of the most significant events in American history, including such incidents as the Whiskey Rebellion, the civil rights protests, the Sioux occupation of Wounded Knee, the Branch Davidian confrontation in Waco, and the arrest of many infamous fugitives.  Until they were tentatively centralized under a director in 1969, many of them acted on their own authority.

Each Marshal is appointed by the sitting president to serve a four-year term, renewable if that president extends his term, and each is assigned to a judicial district. When the Marshals were first formed over two centuries ago, there were only sixteen districts.  Now there are ninety-four.  Within each, the chief deputy Marshals, a career position, is the senior law enforcement officer, serving directly under the political appointee.

The U. S. Marshals Service is now one of five bureaus within the Department of Justice and has the widest range of jurisdiction under the federal code.  The Marshals work with many career deputies, and when necessary, they can quickly deputize state and local law enforcement for special situations.  To date, they have arrested 55 percent of federal fugitives, "more than all other federal agencies combined," and since 1983, they have cleared 145 of the 157 fugitives listed as the "15 Most Wanted."

1. Their duties fulfill five primary missions:
2. Judicial security – to ensure a safe open court environment with 24-hour protection
3. Witness security through the witness protection program
4. Prisoner transport – over 94,000 prisoners are taken into custody each year and 285,000 are moved from one place to another, including by air transport
5. Fugitive investigation and apprehension
6. The Asset Seizure and Forfeiture Program, which deprives drug dealers and money launderers of the fruits of their crimes 

In 1971, a specially trained tactical unit, the Special Operations Group (SOG), was also created to respond in a paramilitary manner to significant civil disorders, terrorism or hostage situations.  They operate as a team to move quickly to contain critical incidents anywhere in the U.S. or its territories.

While many people think of U.S. Marshals as lone lawmen in the Wild West going up against ornery outlaws, in fact the Marshals are present in every state and many of their tasks are administrative.  Even so, over 400 Marshals have been killed in the line of duty, so there's still a sense that men and women who pledge to protect the justice system may face danger as they carry out their duties.  The job is never predictable.

Among the most famous of the U.S. Marshals was Wyatt Earp.  His legend is heroic but the truth is far different. He and one of his brothers were deputy Marshals, and both abused their power for personal agendas.  The famous gunfight at the O.K. Corral was simply a street fight, nothing more. It became a legend based, in part, on the misunderstanding of another Marshal.