In a defamation trial, what matters is not actually what you say, but what ordinary people think you meant. Hannah Marshall of Marque Lawyers explains the theory behind a recent and historic case in Western Australia.

A woman goes missing in Perth one night in 2007. Nine days later her body is found in the bush in Kings Park.

A month later, the police conduct a series of press conferences about their ongoing investigation into the woman's murder. The Detective Senior Sergeant conducting the interviews tells the press that her husband is the prime and only suspect.

Does that mean he's guilty?

This is what happened for Perth barrister Lloyd Rayney after his wife Corryn was murdered. He was eventually charged with his wife's murder in 2010, three years later. He was acquitted of the charges in 2012. The State appealed, and lost.

In 2008, well before he was charged with the murder, Rayney filed defamation proceedings against the State of WA over the police press interviews. Almost 10 years later, and 5 years after being acquitted of the murder charges, Rayney won his defamation case and was awarded $2.6 million, the second largest defamation payout in Australian history. Rayney has since appealed the damages award, claiming $11 million.

Probably the most critical question in the defamation case was what it actually meant to call Rayney the prime and only suspect.

In a defamation claim you have to identify the words that you say are defamatory, and you also have to say what those words mean. It's the meaning of the words (the imputation), rather than the words themselves, that comprise the defamation. The test is what is the natural, ordinary meaning of the words. Unsurprisingly, there's always a heap of debate about the words' meanings, or imputations.

Rayney said that naming him the prime and only suspect was the same as saying that he had murdered his wife. The State, obviously, disagreed.

One reason people get so hung up on imputations is the truth defence. To succeed on a truth defence, you have to prove the truth of the imputations, as opposed to the words themselves. The judge said that the words imputed that Rayney was guilty. This is a big call. Not wrong, but big nonetheless. And fatal for the truth defence, given that Rayney was acquitted of the murder.

Normally, saying that a person has been arrested or charged with a crime doesn't infer that they are guilty. But the Detective Senior Sergeant's words at the press conference went well beyond that, and far enough to infer that Rayney killed his wife. Here's some of what he said.

"Our on-going investigations and forensic evidence have led us to believe it is very likely that Mrs Rayney was murdered at her Monash Street home...." This was an overstatement. At the time, the evidence was some seed pods in her hair, a spot of blood on a piece of flower in her car, and some unanalysed brick dust found on her boots. But, obviously, linking the murder to the Rayney family home would focus people's attention on Rayney as a suspect.

Then press asked where at the house the crime occurred.

PRESS: Can you tell us whereabouts in the house it was that it is likely to have occurred? DSS: No, I don't wish to disclose the, the, exact area that we, we, think that has occurred at. PRESS: Are you able to say if it was inside the actual building or to the outside of the building? DSS: No, I, I don't want to go down that path, it's giving away information that at this stage we would like to keep, umm, confidential. In fact at that stage the police had no evidence to indicate where at the residence any assault had occurred. But the Detective Senior Sergeant's choice of words gave a clear inference that they did know, and they just didn't want to tell the press about it.

The press latched on to the inference of Rayney's guilt. One journo asked did Rayney have accomplices? The Detective Senior Sergeant answered, "Oh, I wouldn't like to speculate on whether this offence occurred, umm, was the result of one or more persons." Importantly, he didn't correct the journalist's assumption that Rayney had killed his wife.

The press questions moved on to the likelihood of Rayney being charged with murder. The Detective Senior Sergeant spoke of the prospect of Rayney confessing and being charged that day.

"... We are interviewing Mr Rayney in relation to the murder of his wife. Umm, pending the outcome of that interview, umm, that would be the only time, if Mr Rayney was to make some level of admission, that would be the only time, today, we would prefer that charge. At this time we have no intention and no evidence to suggest that Mr Rayney is in fact guilty of or is in fact, umm, responsible for this offence." The reference to the lack of evidence connecting Rayney to the offence was redeeming, but not enough to offset the damage of the other parts of the police statement. And later, when asked whether Rayney would be `locked up' here was the answer.

"I, I don't know, I don't know. We've got, we have teams that are working in relation to each of the specific areas of, of this investigation and one team is, is, umm, conducting the interview of Mr Rayney. When they've completed that interview, and subject to, umm, any admissions or confessions he may make, they'll determine what if any offences he's going to be charged with. He will be charged with that particular offence, and then they'll determine his bail and he, he will be released on bail. And whether that's done from Curtin House or whether it's done from East Perth I, I don't know." Here's the thing. Rayney's police interview had finished almost an hour before the press conference started, and he had declined to answer any police questions. So for the police statement to be that the interview was ongoing and that Rayney might confess and be charged, was inaccurate to say the least. Likewise, talking about whether he'd be granted bail when charged, was a dangerous undertaking.

There's more, but this gives you the vibe of the police comments. It seemed crazy at first blush that the judge found that calling Rayney the prime and only suspect imputed that he was guilty. The judge acknowledged that on their own, that might not be the case.

But in all defamation cases, the words are read in the context of the publication. And in the context of everything else the police said, it's not actually so surprising that the judge upheld the guilt imputation.