The Chief Judge of WA's District Court has called for an independent inquiry to be held after a 10-week trial of two market gardeners accused of using illegal foreign workers blew out to seven months.

The judge made the comments when ruling that charges against Michael Le, his brother Minh Canh Le and three other defendants — Jhih-Han Chen, Van Thi Hoang and Huu Cuong Nguyen — should be discontinued.

Minh Canh Le, leaving court today, denied the charges against him. ( ABC News: David Weber )

The men were accused of money laundering and harbouring illegal workers at their fruit and vegetable farms north of Perth.

Outside court, Huu Cuong Nguyen's lawyer, Jonathan Davies, said it was a relief for his client.

"He's immensely relieved that this long nightmare, this travesty, has come to its ignominious conclusion and, indeed, an inquiry called for," he said.

The charges followed raids on the brothers' properties in Carabooda in 2014.

Sorry, this video has expired Trial collapses after seven months

A trial was aborted earlier this year over issues of disclosure of evidence to the defence.

Chief Judge Kevin Sleight told the court today that an accused person was entitled to know about the case against him or her.

'Enormous resources' wasted, says judge

Judge Sleight said it had proved to be an "extremely complex" case and was the result of an "extensive operation" involving the Australian Federal Police, WA Police and other agencies.

A huge number of phone intercepts and analysis of bank records had made the case "extremely difficult to prosecute" and defend, he told the court.

Carabooda brothers Michael Le and his brother Minh Canh denied using illegal foreign nationals to work on their farms and then covering it up in an elaborate money laundering scheme. ( ABC News: Julian Robins )

The costs, the judge said, were "substantial" and probably reached the "hundreds of thousands of dollars".

He told the court the demands on jurors and the Legal Aid Commission, which had been involved in the defence, needed to be considered, as well as the expenses of the sheriff's office and the cost of interpreters.

There was also the psychological burden on the accused, he said.

Judge Sleight said there should be an inquiry into the handling of the case, independent of the Commonwealth Director of Public Prosecutions (CDPP), to consider the "enormous resources" that had been wasted.

But he said he was not calling for a royal commission or an inquiry by a retired judge, rather one that may be conducted by an independent criminal barrister.

Minh Canh Le, Michael Le and a co-accused are still facing other charges and their lawyers have been arguing for a permanent stay.