A federal judge on Thursday dismissed all charges against two brothers accused of bringing 44 laborers from Thailand and forcing them to work on a Hawaii farm.

Federal prosecutors asked U.S. Chief District Judge Susan Oki Mollway to drop all 12 counts against Alec and Mike Sou of Aloun Farms, and the judge granted their request, said Clare Hanusz, an attorney representing many of the Thai laborers.

The brothers were facing up to 20 years in prison without parole if they had been found guilty of the most serious charges. They went on trial after backing out of a plea deal last September that would have given them a five-year maximum sentence.

Prosecutors cited new evidence that surfaced this week in asking Mollway to drop the charges.

Mollway ruled on Tuesday that prosecutors couldn't claim that it was illegal to charge laborers recruiting fees in 2004 when the Sous brought workers to Hawaii. The law was changed in 2009 to prohibit recruiting fees.

Prosecutors had argued the poor laborers were manipulated and deceived. They said the brothers economically trapped the laborers from Thailand into working on the Hawaii farm for little pay while living in metal containers without plumbing.

Federal prosecutors claim the Sou brothers gamed the United States' guest-worker visa system to keep the rural north Thailand laborers on the 3,000-acre Oahu farm, which grows a variety of foods including lettuce, apples, bananas, parsley, watermelon and pumpkin year-round in Hawaii's mild climate.

If the workers complained, they were threatened with deportation. Many mortgaged their homes and properties to pay the recruiting fees, and feared they would lose them, prosecutors said.

But Thomas Bienert, an attorney representing Alec Sou, argued the government ruined the business arrangement when it failed to renew the workers' guest worker visas.

Without valid visas to work in the United States, Bienert said the workers couldn't earn enough money to repay the debts they incurred to travel to Hawaii, but that wasn't the Sous' fault.