Justice Department prosecutors acted with zeal and incompetence in bringing brothers Alec and Mike Sou of Aloun Farms of Oahu to trial for what they regarded as something close to indentured servitude of workers from Thailand.

They traveled back to the nation’s capital without apology after dropping the criminal charges against the Sous at the opening of the fourth day of their trial.

The department’s credibility in the broad area of human trafficking lies tarnished.

That’s hugely unfortunate, since actual cases of human trafficking and worker abuse, once ferreted out, must be prosecuted to the full extent of the law — and that can happen only with a respected, ace legal team.

In the 19th century, tens of thousands of Chinese and Japanese workers were recruited to work on Hawaii’s sugar plantations, contracting to work for a certain length of time while being provided food, clothing and housing. Most of the indentured workers remained in the islands, and their offspring represent much of today’s population.

But in today’s 21st century, stricter labor laws rightly apply, including terms under which foreign workers are recruited and conditions in which they work.

One important aspect of this case was that it had been expected to reveal the treatment of workers, which the laborers contended was inhumane; the Sous refuted that. Now that truth remains shaded from the public spotlight, due to the prosecution’s recruiting-fee blunder.

The Sou brothers entered into agreement to charge 44 Thai workers between $16,000 and $20,000 in recruiting fees in order to work on the farm for $9.60 an hour for three years.

The Sous were accused in court of charging the recruiting fees, but prosecutors realized only after the trial began that the law prohibiting recruiting fees went into effect in 2009. The Aloun Farms workers arrived in Hawaii in 2004.

Susan French, a senior trial attorney in the Justice Department’s Civil Rights Division, admitted that she had inaccurately told a grand jury that indicted the Sous that the brothers could be charged with illegally requiring recruiting fees, even though the legal prohi-bition had not taken effect.

French was abruptly excused from the prosecu-tion team Tuesday because of unspecified health issues. Two days later, federal District Judge Susan Oki Mollway agreed to drop all charges against the Sous.

The dismissal could affect the Civil Rights Division’s case against Los Angeles-based Global Horizons Manpower, a labor contracting business. What the government has billed as the largest human-trafficking case ever prosecuted in the U.S is to go to trial next year before Mollway.

French is the leading prosecutor in that case, which involves the alleged exploitation of 600 workers from Thailand, including some who went to work at Aloun Farms. Michael Green, Global Horizons’ attorney, said the underpinnings of that case are similar to those in the Sou case, although three defendants already have pleaded guilty.

The Global Horizons indictment last September accuses six people of threatening Thai workers from May 2004 through September 2005 to pay recruitment fees ranging from $9,000 to $21,000, complete three years of work or face deportation, even though the recruitment fee prohibition had yet to take effect.

Alec and Mike Sou tried to enter guilty pleas last year but Mollway rejected those pleas because they disputed some of the facts in the prosecution’s case.

Although they still may be named in a civil case brought by the Thai workers, the brothers now have a spotless record.

Conversely, the Civil Rights Division has yet to provide an explanation about its outrageous misconduct.