It is not a defence to an action for defamation that a person was merely repeating what another person said or that the person to whom the defamatory material was published did not believe it. However, there are valid defences that apply, depending on the circumstances of the case. The Defamation Act 2005 sets out a number of defences that expand the common law and create new statutory defences.
The defence of innocent dissemination is intended to protect people such as newsagents, booksellers, librarians and internet service providers (ISP) who unwittingly publish defamatory matter without negligence on their part. However the defence does not stand if the ISP, newsagent etc has the requisite knowledge of the content, however as to exactly what level of knowledge, the law is unclear.
There have been cases that explore the issue of the defence of innocent dissemination. Recent cases have held that an operator of an online search engine can be considered a secondary publisher of defamatory material, even though the operator may not have known that the material was defamatory in nature (see Google Inc v Duffy (2017) 129 SASR 304).
The respondent (the alleged defamer) must prove that every part of the material is substantially true. For example, a person who says that someone is a murderer must prove the fact of murder. Where defamatory matter carries several imputations it is a defence if the reputation of the applicant is not harmed beyond damage caused from those of the imputations which are true [Defamation Act 2005 s 24]. For example, if a publication suggests that a professional person has deceived a client and has taken a client’s money and only one of the imputations is true that may be sufficient to defend the whole publication.
Lord Birkett said in 1951 - 'It is the right of every man to comment freely, fairly and honestly on any matter of public interest.' This principle means it is not defamatory when words are an expression of opinion and not a statement of fact. It may be difficult to determine if words are statements of facts or expressions of opinion. Words must be construed in their context and in some circumstances words that would otherwise be statements of fact might be viewed as comments.
The opinion, however, must be fair and based upon facts which the respondent can identify and prove to be true. It must also be honestly held and not motivated by malice (some improper or dishonest motive). Personal ill will by the respondent towards the applicant is an example of malice. 'Public interest' is a wide concept involving what is a legitimate concern to the public. Instances include the conduct of people holding public office, the conduct of a political party, the conduct of a clergyman and artistic works such as plays and books. It extends as far as the criticism of a restaurant's food in a newspaper review.
The Defamation Act 2005 (SA) s 29 provides a defence of honest opinion where the expression of opinion is related to a matter of public interest and based on ‘proper material’ that is substantially true or based on privileged material.
Consumers leaving reviews online should be prepared to justify their opinion. In Cheng v Lok  SASC 14, the Supreme Court o South Australia awarded damages to a lawyer following a bad review of his services on Google. The plaintiff had never met the defendant, was never retained as the defendant’s lawyer and had never represented the defendant in any capacity. The decision in Cheng illustrates that negative Google reviews will be considered publications for the purposes of the Defamation Act 2005 (SA).
Caution should be exercised when expressing opinions and reviews online, even anonymously.
In Kabbabe v Google LLC  FCA 126 the court made interlocutory orders allowing the plaintiff to serve a court application on Google outside of the Australian jurisdiction for the purposes of seeking preliminary discovery, and to request that Google to reveal the identity of an anonymous online reviewer. The court held the view that this was reasonable, as the plaintiff had a prima facie case for defamation against the reviewer following a negative online review about the plaintiff’s business. The court held the view that it was not sufficient for Google to say that the review had been posted anonymously, as Google had the capacity to identify the person leaving the review.
Some statements are absolutely privileged, so that there can be no action for defamation even if the words were false and were published with malice. Statements that are protected by absolute privilege are those which are made in [s 25]:
information published by the Crown
The Crown (from 2 October 2015) also cannot be sued for defamation for publication of certain other information as set out in the Civil Liability Regulations 2013. The Civil Liability Act 1936 envisages that the Crown may wish to make information public on its own initative rather than in response to a Freedom of Information Act application [s 75A]. Under the Regulations, the Crown has no civil liability for publication of the following types of information [reg 26]:
The defence of qualified privilege allows free communication in certain relationships without the risk of an action for defamation - generally where the person communicating the statement has a legal, moral or social duty to make it and the recipient has a corresponding interest in receiving it. Giving a reference for a job applicant, answering police inquiries, communications between teachers and parents, local councillors, officers of companies, employers and employees, or traders and credit agencies, are all relationships that are protected by qualified privilege. However, the privileged communication must relate to the business at hand - the relationship cannot be abused for the purpose of relaying gossip.
A person who is acting in defence of her or his reputation can claim qualified privilege, as long as what is said is relevant to that defence. It is also available even if what was said was untrue, as long as the required relationship exists. However, qualified privilege is not a licence to say untruths. People making statements must believe that what they say is true.
Government and political matters are proper subjects for public discussion and such discussion is covered by the defence of qualified privilege. To maintain the defence of qualified privilege for such publications the publication must not be motivated by malice and in determining whether there is malice in these cases the court will consider whether the publisher has acted reasonably. The publisher will have to satisfy the court that it has taken proper steps to verify the accuracy of the material and did not believe the material to be untrue and further the publisher's conduct will not be reasonable unless the publisher has sought a response from the person the subject of the publication and has published any response unless it was not practical or it was unnecessary to do so.
In order for the defence to apply, the party making an otherwise defamatory statement must be subject to a duty to make the statement, and the statement must be made to a party bearing a corresponding interest in receiving the information. Examples of circumstances in which the defence may apply include where an employer prepares a character reference for a former employee, or where a corporation makes disclosures required by a government body, such as the Australian Securities and Investments Commission. Where such communications are defamatory in nature, the employer or corporate respondent may be absolved of liability by arguing the defence of qualified privilege.
A fair report of proceedings of public concern is also a defence [Defamation Act 2005 (SA) s 27]. This can include reports of parliamentary, judicial and government proceedings, the proceedings of learned societies, sport and recreation associations, trade associations and meetings of shareholders of an incorporated company.
Although words might appear defamatory, a respondent may establish that they were spoken in jest or as part of vulgar abuse and therefore did not convey any defamatory meaning to those who heard or saw the words. In other words, the words were not taken seriously. The Defamation Act 2005 (SA) also provides a defence of triviality, where the circumstances of publication were such that the applicant was unlikely to sustain any harm.
The Public Interest Disclosure Act 2018 (SA) (formerly the Whistleblowers Protection Act 1993 (SA)) protects people who disclose information relating to substantial risks to public health, safety or the environment, and public officers who disclose information relating to corruption, misconduct and maladministration in public administration.
Provided the information is reported to an appropriate authority (as specified in the Act, see section 5(5)) or in certain circumstances to a journalist or Member of Parliament, the Act gives immunity to the whistleblower [see s 5]. The Act does not protect people who make false or misleading claims [see s 10]. The person must believe, on reasonable grounds, that the disclosure is true [see ss 5(3) and 5(4)].