Every text constructs its own truth. It can mean different things to different people depending on the circumstances, when tested against social mores and attitudes. Post-modern theorists, such as Jean Baudrillard have challenged traditional meanings of truth claiming that truth is an unambiguous entity and that it is truth that conceals that there is none.
The principal representation of truth in The Trials of Oz is Robertson's detailed presentation of the initial courtroom battle, including lengthy quotations from the transcript of the trial. His characterisation of the judge is strongly biased to the point of caricature whereas the editors of Oz are presented as likeable and harmless. Robertson a young lawyer who knew all about the law, but nothing about justice was a stagehand in the defence.
Oz magazine began publication in 1963. Its articles took radical stances on such issues as civil liberties, censorship and the Vietnam War. It's London editors; Richard Neville, Jim Anderson and Felix Dennis had been charged with conspiring to produce a magazine containing diverse, lewd, indecent and sexually perverted articles. Robertson establishes the hypocrisy of the police prosecution, when he explains that at the time pornographic magazines were feely available in London. Robertson's truth is that legally, obscenity was that which would corrupt and deprave, and the mounting evidence suggested that no amount of exposure to indecent to even pornographic material would actually corrupt anybody. Obscenity before the law required much more than something shocking and disgusting it required some seductive invitation to depravity. Hence, Robertson's truth is that the legal definition of obscenity was out of date, and did not apply to this trial, as the mounting evidence suggested that pornographic material could not corrupt anybody.
The composer uses irony and humour to engage the audience's sympathy for the defendants.