Coffman grew up in Great Barrington, Massachusetts, and enlisted in the United States Army in 1972. He graduated from the United States Military Academy at West Point, New York in 1978. Coffman subsequently earned a Master of Science degree in National Security Affairs from the Naval Postgraduate School. He was also a U.S. Army Fellow at the Fletcher School of Law and Diplomacy at Tufts University, and attended the Boston University Overseas Program for Master of Science in International Relations in Vicenza, Italy. In the course of his formal education Coffman has authored papers on ethnic conflict in the post-Cold War world.
In 2004, during the US occupation of Iraq, Coffman was sent as a civilian adviser to train the Special Police Commandos; a paramilitary unit known as the Wolf Brigade that was later accused by a UN official of torture and murder, and which was also implicated in the use of death squads. The Wolf Brigade was created and supported by the US and it enabled the redeployment of Saddam Hussein's Republican Guard but with the new task of terrorising those connected with the Iraqi insurgency. This was part of the US drive to use "dirty tactics" against insurgents in Iraq, a counterinsurgency doctrine known as "fighting terror with terror," and one that had previously been exercised by the US in other theaters, including Vietnam and El Salvador.
Coffman worked closely with Steele advising Iraqi Special Police Commandos during Multi-National Security Transition Command operations, and who has also been implicated in human rights abuses of Iraqi detainees. Coffman reported directly to General David Petraeus and worked alongside Steele in detention centers that were set up with US funding. .
General Muntadher al-Samari, Iraqi interior ministry commander from 2003–05, revealed the US role in torture carried out by the Special Commandos' interrogation units, claiming that Steele and Coffman knew exactly what was being done. Al-Samari described "the ugliest sorts of torture" he had ever seen, which included the severe beating and hanging of detainees, as well the pulling off of their fingernails. The Guardian report also claimed that the US backing of sectarian paramilitary units helped create conditions that led to sectarian civil war.
Coffman has been awarded the Distinguished Service Cross, the Bronze Star Medal, Defense Meritorious Service Medal, Meritorious Service Medal with four oak leaf clusters, Joint Service Commendation Medal with two oak leaf clusters, the Combat Infantryman Badge, Expert Infantryman Badge, Special Forces Tab and the Ranger tab.
Coffman's citation for the Distinguished Service Cross reads as follows:
The Distinguished Service Cross is awarded to Colonel James H. Coffman, Jr., for exceptionally valorous conduct while assigned as the Senior Advisor to the 1st Iraqi Special Police Commando Brigade during a lengthy battle on 14 November 2004 in Mosul, Iraq, during which the unit likely would have been overrun were it not for the courageous leadership of Colonel Coffman and the one Commando officer not wounded. At approximately 1030 hours on 14 November, Colonel Coffman moved with a Commando Quick Reaction Force (QRF) to reinforce a Commando platoon under attack at the Four West Police Station in Mosul. As the QRF neared the besieged platoon, it came under intense rocket-propelled grenade, mortar, machinegun, and AK-47 fire by a large insurgent force. Over the next four hours, the enemy repeatedly assaulted the Commandos' position, at times culminating their attacks twenty meters from Colonel Coffman's location. With all but one of the commando officers killed or seriously wounded by the initial enemy fire, Colonel Coffman exhibited truly inspirational leadership, rallying the Commandos and organizing a hasty defense while attempting to radio higher headquarters for reinforcements. Under heavy fire, he moved from Commando to Commando, looking each in the eye and using hand and arm signals to demonstrate what he wanted done. At one point, an enemy round shattered Colonel Coffman's shooting hand and rendered his M4 rifle inoperable. After bandaging his hand, Colonel Coffman picked up AK-47s from Commando casualties and fired them with his other hand until each ran out of ammunition. With the assistance of the one remaining Commando officer, Colonel Coffman redistributed ammunition among the uninjured commandos until he had only loose ammunition that he loaded by placing magazines between his legs and using his one working hand. Throughout this period, he repeatedly demonstrated exceptional courage and an extraordinary example to the commandos as they repulsed attack after attack by the enemy. Four hours after the start of the battle, a second Commando element arrived and Colonel Coffman guided them to his position. Even after their arrival, he continued to direct the fight, refusing to be evacuated until the enemy was defeated. Shortly thereafter, attack helicopters also arrived, followed closely by a Stryker Brigade QRF, and Colonel Coffman used Iraqi radios to direct air strikes and to provide vital information on the location of enemy and friendly forces. After supervising the evacuation of several dozen wounded Commandos, Colonel Coffman led a squad-sized element to the Four West Iraqi Police Station, fifty meters ahead of the Strykers, to make contact with the Commandos still in the station. After they linked up, the Strykers moved forward, and attack helicopters engaged the buildings occupied by the enemy, following which Colonel Coffman returned to his original position to ensure that all of the Iraqi casualties had been evacuated. Only then did he consent to be evacuated for surgery for his own serious wound. During the fierce four-hour battle, twelve Commandos were killed and 42 were wounded. Twenty-five enemy were killed and many dozens more were wounded.