Mischin denies DNA testing accusation

Western Australia's shadow attorney-general has rubbished claims he knew about systemic problems with DNA testing while in government and covered it up.

Attorney-General John Quigley claimed on Thursday that his predecessor Michael Mischin chose to say nothing to avoid undermining confidence in the state-funded PathWest.

"I challenge him to come up with evidence to establish that or withdraw his comment," Mr Mischin said in a statement.

Mr Quigley's comment was made following revelations a young man agreed to plead guilty to a burglary in 2004, despite protesting his innocence, due to DNA evidence.

PathWest had incorrectly matched the innocent man to DNA belonging to another with the same name because they did not check their birth dates.

PathWest notified police in April last year, but the Director of Public Prosecutions was only told last week when officers delivered a letter to the man.

Mr Quigley questioned why the state government at the time failed to do something about it.

But shadow attorney-general said Mr Quigley had misrepresented earlier comments made about former PathWest chief scientist Laurance Webb, who was sacked last year for breaching testing protocols.

"If I had been aware of the case, I would have taken similar action to that which Mr Quigley has now taken," Mr Mischin said.

He called on Mr Quigley to be "more considered, professional and honest in his public comments".