The bosses of 11 men trafficked from Lithuania and employed to catch chickens should be held liable for their treatment, the High Court ruled.
Darrell Houghton and Jacqueline Judge, of DJ Houghton Catching Services in Kent, knowingly exploited the workers, the court found. They denied liability.
The group worked more hours than they were paid for, and were not given adequate living and working conditions.
Compensation for the men will be assessed at a later date.
“In 2014, the Gangmasters and Labour Abuse Authority described the West Malling company as
"the worst gangmaster ever",and revoked its licence for failing 18 separate licensing standards.
It is the second time a group of former employees who worked on UK farms producing eggs for high street brands have won a High Court ruling.
In June 2016, in separate civil proceedings, judges ruled that the company had failed to pay six Lithuanian workers the due minimum wage; had made unlawful deductions from wages; and failed to provide adequate facilities to wash, rest, eat and drink.
Compensation plus costs of more than £1 were agreed in an out-of-court settlement.
No criminal charges in the UK have been brought against either the company or the couple.
However, director Mr Houghton and company secretary Ms Judge, along with Lithuanian middle-man Edikas Mankevicius, are facing criminal prosecution in Lithuania relating to the treatment of the workers.
The ruling that the couple should be held personally liable for damages to be paid to the workers it exploited follows a four-day preliminary issue trial and an application for a summary judgment in February.
The workers claimed they were trafficked to the UK and promised decent work and good pay, but told how they were put to work in gruelling conditions.
Cup in sink
The men said they were beaten by supervisors, housed in filthy and overcrowded conditions, and deprived of rest.
They also alleged contractual and related statutory breaches, including the failure to pay the due minimum wage, and the systemic withholding of wages for reasons such as leaving a cup in the sink, or for being new to the job.
Giving judgment, the Honourable Mr Justice Lane held that Mr Houghton and Ms Judge "cannot... have honestly believed that what was being done by them to the chicken catchers was morally or legally sound".
Mary Westmacott, a solicitor from Leigh Day representing the claimants, said: "This judgment is a salutary warning to company officers that they may be made personally liable for exploitation of their workers."