An attorney for Tyson employees described the ruling as a "very big step." It allows the lawyers to seek damages for thousands of workers at the eight plants instead of just the four original plaintiffs.

A federal jury in March 2003 acquitted the company and three former managers of conspiring to hire illegal immigrants from Mexico and Central America for low-wage production jobs to boost profits. Two former Tyson managers who made plea deals were each sentenced to one year of probation.

The acquittal dealt a setback to the government's strategy of enforcing immigration laws by going after big business. Prosecutors in the Tyson case relied mostly on tapes of secretly recorded conversations between undercover agents, who posed as smugglers and transporters of immigrants, and former managers at Tyson poultry plants.

Agents testified that they delivered 136 illegal immigrants from Mexico and Central America for Tyson employment. Other testimony said the company tried to shield itself by using temporary employment agencies to find workers, mostly illegal immigrants.

Before the case went to trial, four former employees at Tyson's Shelbyville plant sued. The lawsuit by Birda Trollinger, Robert Martinez, Tabetha Edding and Doris Jewell contends the company violated the Racketeer Influenced and Corrupt Organizations Act by knowingly hiring illegal immigrants who were willing to work for wages below those acceptable to U.S. citizens.

The lawsuit says Tyson relied on a network of recruiters and temporary employment agencies that brought illegal workers into the U.S. and then supplied them with false identification.
Foster said Tyson employees' pay was depressed "probably $8 to $10 an hour" by hiring illegal immigrants.

The eight Tyson plants named in the suit are at Shelbyville; Corydon, Ind.; Gadsden, Ala., Blountsville, Ala., Ashland, Ala.; Sedalia, Mo.; Center, Texas and Glen Allen, Va.