Perth barrister Lloyd Rayney has won his long-standing defamation case against the State of WA over being named by police as the "prime" and "only" suspect in the murder of his wife 10 years ago.

He was awarded preliminary damages of $600,000 for the harm to his reputation, personal hurt and distress caused, with a full compensation amount for Mr Rayney's total economic loss to be awarded at a later date.

Key points: Lloyd Rayney was named the "prime" and "only" suspect in the murder of his wife in 2007

Lloyd Rayney was named the "prime" and "only" suspect in the murder of his wife in 2007 He was acquitted of all charges and launched defamation action over the comments

He was acquitted of all charges and launched defamation action over the comments A judge finds Rayney was defamed, but hopes of a $10m payout seem to have been dashed

But Mr Rayney's hopes of total compensation in excess of $10 million appear to have been dashed, with Supreme Court Justice John Chaney ruling the defamation cannot be held solely responsible for his ongoing economic loss.

In a judgment handed down today, Justice Chaney found the words uttered by then-senior detective Jack Lee implicating Mr Rayney in September 2007, "in their entirety, bore the imputation that the plaintiff murdered his wife."

But he ruled that the defamatory statements only caused him to suffer economic loss through lost income in the three years after statements were made in 2007, when Mr Rayney was charged with his wife's murder.

Justice John Chaney delivers his ruling in Lloyd Rayney's long-running defamation case. ( Supplied )

"... thereafter the defamatory statements ceased to be a cause of economic loss and will not be a cause of loss in the future," he said.

"Rather the damage to the plaintiff's practice from the date onwards is attributable entirely to other causes."

The amount Mr Rayney will be awarded for economic loss in those three years will be determined at a later date.

Lloyd Rayney was not in court for the judgment because he was representing a client in the nearby Perth Magistrates Court, where he left without making any comment.

Lloyd Rayney was not present in the court to hear his defamation victory, representing a client in the Perth Magistrates Court at the time. ( ABC News: James Carmody )

But his daughter Sarah attended in the company of his barrister, Martin Bennett, who said his client was greatly relieved by the decision.

"Of course there is emotion, he is an intensely private man as you all know from watching him and watching him give evidence," he said outside court.

"There is relief because it's the end of a long period."

Martin Bennett and Sarah Rayney speak to a media pack outside the WA Supreme Court after the defamation win. ( ABC News: James Carmody )

He said Mr Rayney was unlikely to get an apology from police, but was expecting a substantial total payout "well above any maximum that's ever been awarded in this State".

Police declined to comment on the judgment, saying there were still legal processes pending.

During the hearing, Mr Rayney's legal team argued for a total compensation payment of $10.7 million, saying his lucrative career as a high-profile lawyer was permanently damaged as a result of the accusations.

The State estimated his losses were closer to $5 million.

These amounts gave rise to predictions Mr Rayney's total payout could end up being the largest in Australian defamation law history, eclipsing the $4.5 million awarded to Hollywood actress Rebel Wilson against magazine publisher Bauer Media.

The 'prime' and 'only' suspect

Justice Chaney found Mr Rayney's reputation and career had been irreparably damaged when Jack Lee — who has since been promoted to Inspector — made the comments in September 2007.

Inspector Lee had been addressing a packed media conference about the investigation into the murder six weeks earlier of Mr Rayney's 44-year-old wife Corryn.

Mr Rayney was charged in 2010 with his wife's murder but was later cleared at trial. ( AAP: WA Supreme Court )

Ms Rayney, a Supreme Court Registrar, disappeared after attending a boot scooting class in the southern Perth suburb Bentley, with her body found eight days later buried in bushland in Kings Park.

Inspector Lee told journalists police considered Mr Rayney to be the "prime" and "only" suspect because they believed Ms Rayney had been killed at the family's Como home, where the barrister was looking after their two daughters, then aged 13 and 10.

"He is our prime suspect because our evidence at this time leads us to believe the offence occurred in that house and he is the occupant of the house," he said. "He is our only suspect at this time."

Jack Lee denied being prejudiced against Mr Rayney when he appeared at the defamation trial. ( ABC News: Eliza Borrello )

From that moment, Mr Rayney claimed his career as a successful and highly-paid barrister was ruined, costing him millions of dollars in income and making him the subject of public ridicule and abuse.

He started defamation action a year later — suing not only Inspector Lee personally but the State of WA, meaning taxpayers would foot the bill if he was successful.

But the action was put on hold in 2010 when he was charged with Ms Rayney's murder.

'A poison incapable of being expunged'

Mr Rayney stood trial before a judge in 2012 and was found not guilty — a verdict that was upheld on appeal.

Then, in 2015, he was acquitted of charges of unlawfully intercepting the landline telephone at the family's home in the weeks before his wife's death.

With those criminal proceedings out of the way, Mr Rayney pursued his defamation action, resulting in a five-month trial in WA's Supreme Court earlier this year.

Mr Rayney's case was spelt out by his barrister, Mr Bennett, who submitted to Justice Chaney that his client had suffered "a dreadful stain on his reputation" that had been "allowed to set firmly in the minds of the people of WA" as a "poison incapable of being expunged".

He said that was despite the police's "fantastically improbable" and "inconceivable" theory that Mr Rayney could have physically committed the crime.

The State, through its counsel Terence Tobin, vigorously defenced the claim, arguing Inspector Lee's comments were reasonable given what police knew or believed at the time.

Marriage breakdown key to State's case

Mr Tobin outlined 33 circumstances and 27 instances of Mr Rayney's conduct that he argued justified the suspicions of police.

Police said publicly they believed Ms Rayney was murdered at the couple's Como home. ( AAP: Liza Kappelle )

They included:

The alleged "acrimonious" breakdown in the Rayney marriage;

The alleged "acrimonious" breakdown in the Rayney marriage; Evidence of Mr Rayney arranging for calls from the home telephone to be recorded;

Evidence of Mr Rayney arranging for calls from the home telephone to be recorded; The belief that the crime occurred at the Rayney home;

The belief that the crime occurred at the Rayney home; Mr Rayney's "lack of co-operation" with police, including not allowing his daughters to be interviewed a second time;

Mr Rayney's "lack of co-operation" with police, including not allowing his daughters to be interviewed a second time; And the statistical likelihood of a woman being killed by her husband.

Mr Rayney was seeking around $10.7 million for lost past and future earnings. ( AAP: Richard Wainwright )

Mr Rayney spent days in the witness box being cross examined by Mr Tobin, defending his conduct.

He testified that, at the time of his wife's death, he believed they were reaching an amicable agreement about their marriage breakdown, and he maintained he had recorded their conversations with her consent.

He also said actions after her death were a result of fears that police were trying to frame him for murder and send him to prison for the rest of his life.

One-by-one, the detectives who worked on the case — including Inspector Lee — were called to give evidence, to defend their belief in September 2007 that Mr Rayney was "the most significant suspect".

Some, including Inspector Lee, said they still had that belief despite Mr Rayney's acquittal.

There was also testimony from members of Ms Rayney's family, including her brother-in-law Rohan Coutinho, who said he believed at the time and still believes that Mr Rayney killed his sister-in-law.

The case for historic damages

Justice Chaney also heard submissions about how much compensation Mr Rayney should receive if he was found to have been defamed.

The barrister's side argued that as well as damages for "non-economic losses", he was entitled to around $10.7 million for his lost past and future earnings.

Mr Rayney has since resumed his career as a barrister, but he maintains — because of Inspector Lee's comments — that he is not at the same level he once was and has no hope of ever being appointed as a Senior Counsel or Judge.

The State estimated his losses were a lot lower, closer to $5 million.

The initial $600,000 payment awarded by Justice Chaney was for damage to Mr Rayney's personal business reputation, personal hurt and distress caused by the defamation.

The total payout for the economic loss had has suffered will be decided at a later date.

The State has 21 days to lodge an appeal.