The bad news is, less than two-thirds of have heard of the Australian Constitution, a new survey has found.

The Ipsos MORI survey was commissioned across 23 countries as part of the commemorations of the Magna Carta's 800th anniversary.

More than 1000 Australians were surveyed, of whom 65 per cent had heard of the Australian Constitution, 59 per cent of the US Declaration of Independence, and 53 per cent of the Magna Carta.

Aussie awareness of the old document which established, among other things, the rule of law over the king, the right to trial by jury and the freedom from arbitrary arrest, was significantly higher than the international average of 39 per cent.

Great Britain and the USA did best, Australia came sixth of the countries surveyed behind Spain, Italy and Hungary. Only six per cent of the French said they were aware of it.

The survey did not explore whether Australia's knowledgeable score was thanks to a successful educational system, the popularity of the (hideously ahistorical) Russell Crowe Robin Hood movie, or what you might call "The Castle" syndrome.

According to the Australian Senate website, "Magna Carta is much quoted by Australians when they are representing themselves in court cases."

Some of its clauses are still part of Australian law inherited from the UK, though actually citing it in court is usually considered the sign of a rank amateur.

The survey also found that:

- 39 per cent of Australians felt that freedom of speech was under threat today in Australia, 35 per cent felt basic human rights were under threat, and 27 per cent chose freedom of religion.

- In China, the survey organisation was not allowed to ask which rights people felt were under threat. Most other countries came up with similar answers to Australia, but India was more concerned with equal rights for women, and Russia with freedom from arbitrary arrest.

As part of the anniversary this year, Australia's 1297 copy of the Magna Carta will be removed from its glass case at Parliament House for the first time in 50 years. It will be digitally scanned, examined by conservation experts then placed in a new display case.

The original was sealed (not signed) at Runnymede by King John on June 15 1215, to settle a rebellion by powerful barons.

Its 12th clause, that no tax should be levied without common consent, was the seed that grew into the modern parliamentary system.