Simon Rice.

Simon Rice. Photo: Peter Morris

It's not hard to know when you've been discriminated against; it's much, much harder to prove it.

After almost 50 years of federal, state and territory anti-discrimination laws, this is a major failing in the protection they offer, but one which the federal government will remedy in its proposed new anti-discrimination law.

At the moment the person who is complaining of discrimination has the burden of proving what happened. The proposal is to share that burden between the person who is complaining and the person whose conduct is being complained of. Despite what some commentators say, this is not a ''reverse'' onus: no one is going to be ''guilty until proven innocent''. It is a shifting or shared burden. It is a fair and sensible approach, with a solid history behind it.

To get protection from anti-discrimination law, an aggrieved person has to prove what the alleged discriminator already knows. But the person can usually complain only on the basis of a suspicion that they were discriminated against, such as being refused rental accommodation because they had children, or ostracised in their club because of who they married, or refused a job because of their family responsibilities. It is the landlord, the club or the employer who knows why they acted as they did.

Instead of giving those who know why they acted as they did the chance to explain themselves, anti-discrimination laws require the aggrieved person to try to prove it.

Proving what was in another person's mind is almost impossible, and relies largely on circumstantial evidence, inference and cross-examination.

To give the aggrieved person something to work with, anti-discrimination law in Australia has relied on a particular device: the ''comparator''. It is supposed to be easier to prove that there was discrimination if you can show how the alleged discriminator treated someone else (the comparator) in the same circumstances. But experience tells us that this just doesn't work: either the alleged discriminator has information about the comparator, or the comparator is a fellow worker who doesn't want to be dragged into court, or there isn't a comparator and everyone guesses what might have happened hypothetically.

This means that an anti-discrimination case can run for two or three days while the aggrieved person spends time and money trying to prove their case, and the alleged discriminator spends time and money watching and waiting until it is their turn to tell their story.

Australian labour law recognised this problem of proving what is in another's mind as long ago as 1904. Ever since then - most recently in Work Choices and in the Fair Work Act - if an aggrieved worker has enough evidence to reasonably suggest unlawful conduct, then an employer is asked to explain their conduct. The burden of proof is shared, shifting from an aggrieved person who can show an arguable case to an alleged discriminator who can explain their conduct.

As Justice Northrop said in 1976, ''the circumstances by reason of which an employer may take action against an employee are, of necessity, peculiarly with the knowledge of the employer.'' This is the sensible reasoning behind the federal anti-discrimination law proposal. And with a shared burden of proof anti-discrimination law can drop the cumbersome, expensive and ineffective ''comparator'' exercise.

Without any controversy, another area of federal anti-discrimination law has had a shifting onus for many years. If a person imposes a ''neutral'' requirement that has a discriminatory effect on some people because of, say, their disability, age, or child-caring duties, the onus is on the person imposing the requirement to explain why it is reasonable in the circumstances. This makes sense (and has been unremarkable) because it is the person imposing the requirement who knows and can explain why it is necessary.

I have advised and represented anti-discrimination complainants for many years, and as a tribunal member I have decided many cases. A lot of cases would have finished much sooner - proved or disproved - if the burden had been shared.

As it is, over 90 per cent of anti-discrimination cases never get to court. Most are resolved in conciliated settlements by the Australian Human Rights Commission. A debate over a shared burden is only directly relevant for the few matters that are contested all the way.

For those matters, a shared burden of proof is a logical approach to proving why someone acted as they did. It is an approach with a long and unremarkable pedigree in Australian labour law.

It saves time, money and stress. Bringing it into anti-discrimination law is both sensible and fair.

Simon Rice teaches law at the ANU College of Law, where he researches and writes on anti-discrimination law, and is a former judicial member of the NSW Administrative Decisions Tribunal.