By Juan Forero

In 2001, paramilitary hit men pulled three union leaders off buses in this roasting-hot swath of northeastern Colombia and shot them dead. In a shadowy conflict where gunmen often kill union activists, the slaying generated little attention, even as the dead men's families accused their American employer of having ordered the hits.

Now, six years later, the spotlight is on Drummond Co., the Alabama-based coal producer that employed the men. This week, in a federal court in Birmingham, the company has begun defending itself in a civil suit in which the families of the slain union members are seeking unspecified damages for their deaths. Drummond has denied allegations that it ever worked with paramilitary groups or played a role in the deaths.

The case marks the first time an American company has gone before a jury in a U.S. court for alleged abuses committed abroad. The trial is expected to generate scrutiny from other federal benches and the Supreme Court, which in 2004 upheld a ruling that foreigners could sue in American courts for abuses abroad -- but under narrowly defined legal boundaries. A key question is whether federal courts will be inclined to hold corporations responsible under the arcane 18th-century law -- called the Alien Tort Claims Act -- that was used to take Drummond to court.

"I think it has enormous significance," Martin Flaherty, a professor of international human rights law at Fordham Law School in New York, said of the trial. "That's really what this suit and other suits like it will answer -- the role of corporate responsibility."

Filed by lawyers for the Washington-based International Labor Rights Fund, the suit comes in the midst of a long scandal in Colombia that has exposed ties between illegal paramilitary groups and the political, military and business establishment. Investigators in Colombia have shown how paramilitary members expanded their operations across much of the northern coast, including this region, with the help of corrupt politicians and army officers.

The slayings of union members has increasingly attracted attention in the U.S. Congress, which in a hearing last month scrutinized evidence that Drummond, along with Chiquita Brands International, an Ohio banana firm, allegedly helped support paramilitary groups. (In March, Chiquita admitted in D.C. federal court that it had paid paramilitary groups $1.7 million but asserted it did so to protect its workers.) More hearings on the issue are planned, said Rep. Bill Delahunt (D-Mass.), who chairs the Foreign Affairs subcommittee on human rights that called for the June hearing.

"We have to monitor that behavior and sanction those that engage in that kind of activity," Delahunt said.

Drummond said it would not comment about the case, and its officials did not return phone calls. But in court Wednesday, Drummond's lead attorney, William H. Jeffress Jr., said, "The allegations of the plaintiffs are not true, and they're not fair." Jeffress said Drummond wouldn't have risked its investment by resorting to murder.

Nevertheless, the avalanche of revelations in the so-called para-political scandal has touched Drummond, a company that is close to the administration of President Alvaro Uribe and central to the production of one of Colombia's most important exports, coal. Drummond has sunk more than $1 billion into developing its mine here and produces more than 25 million tons of coal a year.

Several new witnesses have surfaced in recent months to allege that in an effort to fight back against Marxist guerrillas who attacked the company's coal trains in Cesar state, Drummond came to depend on fighters from Colombia's coalition of paramilitary groups, the United Self-Defense Forces of Colombia, or AUC. Funded by ranchers and businessmen, the AUC morphed into a terrorist group engaging in drug trafficking and mass murder.

Its backers "feared attacks on the rail lines, on the port, on the mines," explained Rafael Garcia, a former high official in Colombia's secret police who has become a government witness here revealing ties between paramilitary commanders and politicians.

Among the witnesses who have come forward here is Edwin Guzman, a former Colombian army sergeant whose unit, the Popa battalion, deployed hundreds of men inside Drummond's installations.

Guzman said in an interview that Drummond provided transportation to paramilitary units and that the company's chief of security coordinated military-paramilitary operations. The Popa's former commander, Col. Hernan Mejia, was cashiered and is being investigated for having allegedly collaborated with paramilitary groups.

Guzman said Drummond officials knew full well how the paramilitary groups operated. "Seven hundred soldiers can't do what two paras can do, since the paras don't capture, they just assassinate," he said.

Drummond has its defenders, including Rep. Dana Rohrabacher (R-Calif.), who has said he does not believe Guzman's allegations against the company. In a recent interview, Colombian Vice President Francisco Santos said, "I have no doubt that this was not company policy."

Much of the case against Drummond is based on circumstantial evidence. Additionally, some of the witnesses for the plaintiffs were themselves involved in paramilitary activities or other crimes, raising questions about their credibility.

"Certainly that's going to be a problem," acknowledged Terry Collingsworth, general counsel at the International Labor Rights Fund. "Drummond is going to argue, 'The guy's the devil, and how are you going to believe him?' "

Still, Collingsworth said, there are witnesses such as Isnardo Ropero, who was a private security guard for a Drummond official, and George M. Pierce, an American who worked in La Loma for two years. In a sworn statement, Ropero said paramilitary groups provided security services for Drummond, and Pierce described in trial testimony how Drummond's chief executive in Colombia, Augusto Jimenez, made a veiled threat against labor leaders. Pierce has also said Drummond officials presumed that union members were nothing short of rebel collaborators.

"They chose a side in the war," Herman N. "Rusty" Johnson Jr., an attorney for the plaintiffs, said of Drummond. "They chose the paramilitaries."

What has not been in dispute is that the AUC killed the union leaders whose families have now brought suit. Valmore Locarno, the local union president, and his vice president, Victor Orcasita, were slain on March 10, 2001. Not quite seven months later, Gustavo Soler, Locarno's successor, was shot dead. A feared commander, Rodrigo Tovar, has been charged with the slayings, and Attorney General Mario Iguaran has said prosecutors are investigating paramilitary groups' ties with Drummond.

Nor is there much disagreement over the AUC's influence in the late 1990s and early in this decade, a time when Drummond was also expanding. With financial and political backing, the AUC took control of the dusty, poverty-stricken towns all across Cesar.

While its fighters eroded the rebels' support base, they also forced the smallest businesses to make extortion payments and had local officials kick back a percentage of all public contracts.

"They dominated military, massacring people, dismembering people, leaving people dead on the highways," said Alfonso Palacio, candidate for mayor in the town of La Jagua and a government witness against paramilitary commanders. "They generated a collective psychological terrorism in the region."

Among those left devastated by the violence is a woman in her 40s who had a child with Orcasita, the former vice president of the Drummond union.

"The damage was great, just too much, too much," said the woman, a plaintiff who was granted anonymity in the case for fear of reprisals. "All these years I've been alone with my daughter. Going through hard times, cruel times."