Western Australia's Police Commissioner has launched a scathing attack on a parliamentary committee that investigated a series of crashes involving former treasurer Troy Buswell, accusing it of manipulating the facts.

In February, the then-treasurer crashed his ministerial vehicle into several cars in Subiaco on his way home from a wedding.

The Member for Vasse subsequently relinquished his treasury and transport portfolios, and was later fined and disqualified from driving for a year after pleading guilty to several offences related to the incident.

A Labor-dominated parliamentary committee investigated WA Police's handling of the incident, labelling it "inadequate" and concluding there had been "systemic failure at a number of levels".

In the Government's damning response to those findings, tabled in Parliament today, Police Commissioner Karl O'Callaghan argued the committee's report was littered with incorrect assumptions and conclusions, many put forward without a "scrap" of evidence.

He described the investigation as the most biased parliamentary inquiry he had ever been involved in.

"The committee's had a pre-determined position in mind, a pre-determined outcome, and they've manipulated the facts that we've provided them to fit their pre-determined outcome," he said.

"What the committee's done is they've simply formed something in their mind that they wanted to say and they've taken the evidence that we've given them and manipulated it to fit that particular outcome."

In his response, Mr O'Callaghan stated the three Labor members of the committee, including chairwoman Margaret Quirk, had "only a rudimentary understanding of police investigation and response".

"The value of the report as object advice for improving police investigations is limited by conclusions that have no basis in fact," he said.

The State Solicitor's Office has also criticised the committee, accusing it of potentially compromising and impeding high-profile police investigations.

In the report, the office stated the committee set an "unusual and dangerous" precedent when it decided to publicly release confidential witness statements.

"The committee's decision to also simultaneously release to the public two witness statements was unorthodox and inappropriate," it said.

"They are usually obtained and made on the understanding of confidentiality, and generally the documents will only be disclosed to the parties and the courts on a necessary basis.

"Police investigations into high-profile public figures would be impeded and compromised by any diminution of the accepted regime of discretion and confidence."

Labor stands by report

Labor leader Mark McGowan has defended the committee's conduct and said he stood by the findings.

"It's not the committee that covered this up, it's not the committee that didn't reveal the facts for two weeks until a witness came forward," he said outside Parliament.

"It's the Government that has the questions to answer here, and they haven't answered major questions in relations to this matter since this tawdry affair came up."

Mr McGowan also defended the committee's decision to publicly release the witness statements, saying it was a routine procedure in courtrooms around the state.

"I'll explain to you the court process. When you provide a statement to police, you are then subject to appearing before a hearing before the courts, so they are open almost invariably," he said.

Premier Colin Barnett has released a statement calling for Ms Quirk to resign as chairwoman of the committee.

Ms Quirk has refused to comment.