In an unrelated action, the Whaleoil blogger told the High Court he should not have to reveal who supplied him information he used for a series of posts because he was a journalist.
He claimed Evidence Act protection of a journalist's sources. Justice Raynor Asher found Slater was a journalist by virtue of regular publication on his blog.
But he ruled that Slater could not have the protection for his sources offered by the law because there was no public interest in keeping their identities secret.
The reason for the loss has a bearing on the Hager case and on journalism now the internet makes it possible for anyone to be a publisher, or a journalist.
Police have accepted Hager is a journalist. In Slater's case, Justice Asher also found he was a journalist but focused on the work he produced.
He found a journalist's protection of sources should "promote the free flow of information, a vital component of any democracy", adding, "This factor would appear to have particular relevance where the facts and opinion that are the subject of the communications are of public interest and significance."
Journalism seeks no special privileges or rights other than those which are conveyed by the public interest purpose it serves.
Its relationship with sources is as a conduit for information it believes to be of such genuine importance that it must be conveyed to wider society.
There is no magic shield called journalism behind which journalists can hide their sources. The only shield available is that of justice, and a wider public interest, as highlighted by Justice Asher.
Slater's was a defamation case. Hager's is a criminal investigation. Justice Asher found Slater's work - at least in relation to the case before the court - did not meet the test of public interest. Did Dirty Politics serve the "public interest"?
Putting aside political allegiances, the book did shine a light on aspects of the modern political world which had previously been in shadow. As a result, the public is better informed about the way our democracy operates.
The Supreme Court's ruling suggests receiving illegally obtained email may be a crime.
On this basis, Hager's challenge to the police search of his house may be harder to sustain. But since his book served a public interest, free speech should prevail.
Debate on this article is now closed.