For people who have committed crimes, however, there is a clear incentive to obfuscate, and to prevent investigators from obtaining the truth. Under Australian law, juries are not able to draw an inference of guilt from a defendant who chooses not to disclose key elements of their defence to police investigators. For professional criminals, the right to silence is therefore an important tool that allows them to gain a tactical upper hand during criminal trials. This is not only frustrating for police, it degrades the integrity of our legal system. Criminals know they can exploit the system and get away with it. Amending the application of the right to silence, or setting out new defence disclosure obligations, would make it more difficult for criminals to escape justice through the use of shady legal tactics. Britain (where the right to silence originated) has already gone some way to addressing this problem through the Criminal Justice and Public Order Act 1994. This act permits the court to draw an adverse inference from a person's failure to disclose vital information during the police investigation, in certain circumstances. It does not remove the right to silence, but modifies it, so that facts the accused will rely on can be fully investigated before trial.

It also has safeguards to prevent police abuse. This act has empowered the courts and has had no effect on the right to a fair trial. The right to silence was established under English common law in the 17th century as a protection against the arbitrary actions of the state. Today's courts, however, are not royal inquisitions or star chambers, and the power of the state is now limited by the doctrine of separation of powers. A subtle modification of the right to silence in NSW, therefore, would stop criminals exploiting a historical anachronism in our justice system, without sacrificing the basic principles of justice, or affecting the rights of innocent people.

Scott Weber is the Police Association of NSW president. THE LAWYER NICHOLAS COWDERY LET'S be clear - there is no "right to silence". We all have obligations to each other created by real rights and responsibilities and society works best when we co-operate in the proper exchange of relevant information for lawful purposes. The closest expression of a general protective principle is found in the International Covenant on Civil and Political Rights, reflected in our laws - a right not to be compelled to testify against ourselves or to confess our guilt. Fair enough - the days of thumbscrews and the rack are over. The "right" in reality privileges us against those compulsions (or indeed, having to say anything much during an investigation or trial). Our silence in those situations cannot be used against us to infer guilt. But there are qualifications - the privileges are not absolute. For example, a car driver can be compelled to identify herself and produce a licence; an accused person must provide notice of an alibi before trial. This collection of privileges has been created over the centuries in the evolution of our criminal justice system, especially through times when there had been systemic abuses by officials, when accused persons generally were more ignorant and illiterate, could not give evidence in their defence and could not be legally represented. As general levels of education in the community rise and the legal system evolves more fairly, we should constantly review what information can be withheld from "the authorities" and in what circumstances.

The present shooting spree in Sydney (a temporary aberration) sees people affected unwilling to co-operate with police. That is their privilege; and there are already offences in place of concealing serious offences and hindering investigations to provide some balance. Special and exceptional bodies which are subject to much greater degrees of oversight and control than the Police Force, such as the Crime Commission, have additional powers to question people and it is an offence to refuse - but any self-incriminating evidence cannot be used against the provider. That can be a useful tool, but should be used sparingly and certainly not given to police at large. There are significant private and public costs of applying that regime. How do you legislate (or lawfully act) to compel people to provide information that they may or may not have? How do you prove that somebody knows something they're not telling you? As in all things in the criminal law, a proper balance is required to be struck and the balance we have reached over a very long time under the rule of law is about right. Nicholas Cowdery, QC, is the former director of public prosecutions. THE ADVOCATE ROBYN COTTERELL-JONES

ALL arguments in this debate are reasonable and that's what makes it so difficult. Politicians must react to public distress, fear and calls for action; the police cannot investigate properly if they are locked out by people's refusal to speak; people who expect retribution from offenders if they inform on them have a right to be safe; and there is a code of silence among offenders. So what is the answer? Those who have been exposed to these shootings were certainly at risk of physical harm, and no doubt emotional trauma. Our law does not discriminate about the right of all people to be safe, irrespective of their links to illegal activity, if that is the case here. The last thing we need is more victims, more families harmed forever by firearms - especially when you add the high probability of their being let down by the criminal law as it repeatedly favours the rights of an accused over any law-abiding citizen. What I do know is that when it comes to the right to silence, victims and witnesses should not be treated the same as the accused. Unlike an accused, whom police must warn of their right to silence before questioning them, victims are not given any warning. In fact, they are often told they must make a statement and be compelling and accurate or the matter will not proceed. Cases are often lost because of that failure to inform the victim of the impact of any admission. Victims are also sometimes charged because of admissions they inadvertently make.

I worry how those forced to give information or evidence under threat would receive protection. How would they be shielded? The AVO process does not seem adequate. If a witness were coerced or threatened into giving evidence, how would that play out in court if a trial eventuated? A Crown witness already has a challenging task, but a reluctant or hostile witness might prove unhelpful to a prosecution case. In their minds will be the knowledge that crossing prosecutors is unlikely to get them shot or their homes destroyed. Crossing shooters, on the other hand … There is no simple answer. Robyn Cotterell-Jones is executive director of the Victims Of Crime Assistance League.

THE ACADEMIC MIRKO BAGARIC THE right to silence has a long and non-distinguished legal history, dating back centuries. Like most rights, it is popular among lawyers and civil libertarians but no one has yet been able to show why it must be observed in all instances. This has dawned on most governments and, in the past decade, an increasing number of investigative bodies have been given power to compel people to answer questions about their knowledge of criminal acts. However, the legislation is patchy and driven by political ideology. Thus, organisations such as the Australian Crime Commission and NSW Crime Commission, whose activities are normally confined to serious criminal matters, are given power to compel witnesses to answer questions, but so too is the Australian Building and Construction Commission, which looks at relatively trivial matters. A more principled solution is necessary. People like rights because they ostensibly protect them from the actions of governments and other people. But the exercise of rights by one person can have a detrimental impact on others and the community.

A balance needs to be struck. Individuals should be free from unfettered police questioning and not readily be placed in situations in which they may be required to betray a loyalty to a friend or relative and give information that may be adverse to them. This can place them in stressful situations and lead to more people being charged with criminal offences. Yet we all live in communities and this carries some sense of obligation, which in rare cases requires people to sacrifice their immediate interests for the common good. In the context of the right to silence, this means that in relation to very serious crimes individuals should be required to tell police what they know about the offences. It is difficult to prescribe the level of offence severity at which point this is reached. However, studies show that the offences which affect victims most significantly are serious sexual and violent offences. Property and other offences, including drug offences, are less damaging. Thus, in relation to serious sexual and violent offences, people should be required to assist police. In relation to other offences, we should be free from unwanted questioning.

Mirko Bagaric from Deakin University is the co-author of Australian Criminal Law.