A trial in WA's District Court has been aborted in extraordinary circumstances, with a jury that was sworn in for a 10-week trial being discharged after the case ended up running for more than seven months.

Key points: 18 jurors was sworn in for a 10-week trial that lasted seven months

18 jurors was sworn in for a 10-week trial that lasted seven months By February just 12 jurors remained — the minimum required

By February just 12 jurors remained — the minimum required Delays were caused by repeated disclosure issues

Delays were caused by repeated disclosure issues Jury discharged on Friday "in the interests of fairness"

The seven men and five women were told on Monday morning by Judge Stephen Scott that the trial had "gone off the rails" and despite their seven months of "resilience", they were being discharged from their duty to return verdicts.

They were selected in mid-October last year to hear the case of once successful market gardeners, Michael Le and his brother Minh Canh, who were accused of using illegal foreign nationals to work on their fruit and vegetable farms and then covering it up in an elaborate money laundering scheme.

The brothers, along with three others, had been charged after high-profile raids on their properties in Carabooda, north of Perth, in 2014, involving dozens of officers from the WA and federal police as well as the Australian Border Force and other Government agencies.

Brothers Minh Canh and Michael Le and denied the charges against them. ( ABC News: Jon Smball )

All denied the allegations.

After four years of investigation, it took three years for the case to get to trial and a jury of 18 was finally selected — six more than the 12 required, but as is the usual practice, the extras were sworn in to cover any unforeseen circumstances, such as illness, which meant a juror could not continue.

Beset by problems from the start

Four of the five accused were assisted in the dock by an interpreter, but virtually from the start the trial was beset by problems centred around the issue of disclosure by the Commonwealth authorities involved.

Disclosure is the obligation of the prosecution to provide defendants with all relevant materials so it is clear to them exactly what is the case against them, and in this trial it was an ongoing process.

Sometimes thousands of new documents were produced — mainly details of telephone intercept material — that required adjournments to allow the defence lawyers to examine them, and then to argue before the judge about their admissibility.

By February, the fourth month of the trial, the jury was down the minimum number of 12.

That led to more adjournments, not only for legal argument but also to accommodate the increasingly frustrated jury members by letting them take holidays they had booked, attend appointments and get hospital treatment.

One of the Carabooda properties raided by Australian Federal Police. ( Supplied: AFP )

One jury member was so committed, however, they chose not to attend a family celebration in the eastern states.

The trial lurched on with more disclosure, more legal argument and more adjournments. Since January 23, the jury has spent 40 days out of court, an amount of time Judge Scott described as "staggering".

The tipping point came two weeks ago when the prosecution produced a further 53,330 intercepted telephone calls, which all concerned believed would require a six-to-eight-week adjournment for the defence to analyse.

Trial 'off the rails'

Last week Judge Scott heard another application to abort the trial and this time he agreed, saying a further lengthy adjournment was unacceptable and it was now time to discharge the jury in the interests of justice.

Dozens of officers were involved in the raids on the Carabooda properties. ( Western Australia Police )

Judge Scott said he had never before presided over a trial where he felt that "in the end it had gone off the rails", and the case had reached the point where "the interests of a fair trial trumped the public interest".

"I have no doubt the lack of timely disclosure is the factor that caused this trial to go off the rails to an impermissible extent," he said.

He said the most recent disclosed material was known to the Office of the Commonwealth Director of Public Prosecutions (CDPP) in 2015, but was not disclosed to the prosecutor in the case and was either "mislaid or not acted upon" until mid-April 2018.

In explaining his decision to the jury, Judge Scott thanked them for their "persistence and resilience" telling them they had not signed up for such a lengthy trial that the authorities had "hopelessly underestimated."

Before the court adjourned, barrister Lloyd Rayney, who represented Michael Le, described the case as "extraordinary".

"Every right-minded person has the right to be outraged at the enormous cost of this to the community," Mr Rayney said.

'It's cost me my life': accused

Outside the court his client also expressed his anger, describing what had happened as "unfair".

Mr Le said the whole case had ruined his business.

A number of government agencies were involved in the raids on the properties. ( ABC: Emily Piesse )

"You can't run a business and sit here for seven months," he said.

"In the end for disclosure not to come out — it's just wrong, it's really, really wrong.

"It's cost me my life, just being here away from my family, away from work. No time for family, no time for my kids."

Mr Le said he also felt sympathy for the jury.

The five accused now face the prospect of a retrial, although they are expected to make an application to put the case permanently on hold.

In the meantime they have been released on bail until they appear in court again next month.

In a statement the CDPP said it was committed to ensuring all accused people were provided with the material they need to obtain a fair trial.

The CDPP said further legal proceedings in the case were scheduled before the District Court in Perth.