As we confront the real world threats that terrorism offers up, we have to be careful that the balance between preventing the unimaginable, and punishing what is only imagined, doesn't tip too far either way, writes Michael Bradley.

Witwer: "I'm sure you've all grasped the legalistic drawbacks to pre-crime methodology ... we are arresting individuals who've broken no law."

Jad: "But they will."

The film Minority Report is based on the sci-fi premise that the future can be seen and a crime can be prevented before it happens. The only difference between that fictional construct and the new era of thoughtcrime into which we are drifting is that we cannot know what bad thing is going to happen, but we are seeking to prevent it all the same.

That we do have something to fear was brought home by the senseless murder of Curtis Cheng by 15-year-old Farhad Jabar. That this was an incident of extreme rarity is no comfort to Mr Cheng's family, nor does it soothe our dread of terrorist acts (that's the point, after all).

The anticipation of just such a thing has been driving every government since 2001 to implement law after law which closes the net more tightly around acts of violent extremism before they can occur. Apart from the human impulse to prevent random violence altogether so that we can feel sufficiently OK about continuing to live, for the legislative and executive arms of government there is the determination to not be asleep at the wheel; nobody wants to risk missing the signs of a 9/11 ever again.

The reality, that terrorism constantly metastasizes (Bali, Madrid, Charlie Hebdo) and cannot be contained, is not a reason to do nothing.

The case of Omarjan Azari demonstrates both the problem with which authorities are grappling and the risks which are inherent in their response. Azari was arrested in September 2014. Police had recorded phone calls between him and Mohammad Ali Baryalei, a notorious Australian member of Islamic State, including this conversation:

Baryalei: "What you guys need to do is just pick a random unbeliever. When finished put the flag of the state in the background and film it and send it off."

Azari: "Yeah."

Baryalei: "Backpacker, tourist, American, French or British even better."

Police recorded phone calls between Omarjan Azari and Mohammad Ali Baryalei (pictured). ( ABC )

Azari's defence counsel has told the court that Azari repeatedly indicated to Baryalei that he was under heavy surveillance, and then said, "For this reason, let [sic] abandon this plan for a couple of months Allah willing after that I will get another phone and start the work." According to the defence, in a later translation of the conversation, "abandon" was changed to "postpone".

Azari was initially charged with conspiring to commit a terrorist act, but this was later dropped and replaced by a charge of conspiracy to murder. The essential elements of a crime of conspiracy are an agreement to commit a particular crime and the commission of an "overt act" towards carrying the agreement out.

Azari is also accused of doing an act in preparation for, or planning, a terrorist act. A specific terrorist act need not have been identified. In addition, he has been charged with making funds available to commit a terrorist act. The evidence relating to this aspect has not been made public.

Azari is 21 years old and has spent the past 14 months on remand in Goulburn Supermax. He's facing anything up to life in jail if convicted. I have no opinion to express on him or the charges against him. A magistrate will decide whether he should stand trial; if he does, a jury will determine his guilt or otherwise.

My interest is in how his case illustrates the difficulties of prevention by punishment - pre-crime, if you like.

Our criminal law has never sought to punish us for crimes we thought about, intended to commit or planned in our heads, but didn't carry out. The crime of conspiracy (to commit a crime) was the closest it ever came, and it requires both a meeting of two or more minds and action towards the crime itself - much more than just the harbouring of murderous intent.

Hopefully I don't have to explain why we haven't criminalised our thoughts; I'll just point you in the direction of George Orwell and/or the Cultural Revolution if necessary.

I'm not saying that it should not be a crime to plan a terrorist act or a violent crime. I do believe that punishable crime should consist of more than the goings-on inside a person's own head, or the content of a conversation. The evidence must establish that a crime was going to be committed; otherwise we are elevating thoughtcrime to the same status as the physical act.

People charged with these types of offences present us with a terrible dilemma. We dread what they might have done if not detained, and we are impelled to turn the evidence of their words and thoughts against them, to lock them up for what they thought to do. Thus, we prevent something dreadful which might have happened. In doing so, we implicitly acknowledge that the privacy of our own thoughts, the previously inviolable domain of what happens in our own heads, no longer has primacy over the greater interests of society as a whole.

We are taking this step more or less consciously, because we really do fear terrorism and we will do almost anything to prevent it. I don't think, however, that we know what we're doing.

Orwell's future was as dystopian as Philip K Dick's. We're nowhere near 1984, but we're not a million miles off either:

The Party takes loyalty seriously, and does not tolerate any acts of subversion - even if they are mere thoughts.

As we confront the real world threats that terrorism offers up, we have to be careful that the balance between preventing the unimaginable, and punishing what is only imagined, doesn't tip too far either way.

Michael Bradley is the managing partner of Marque Lawyers, a Sydney law firm, and writes a weekly column for The Drum. Follow him on Twitter @marquelawyers.