The Panama Papers proved that once you out peoples' dirty secrets, their game is largely up.

To date, it remains one of the biggest data leaks in history, revealing the hidden faces behind shell companies and offshore tax havens.

The 11.5 million documents, leaked from Panamanian law firm Mossack Fonseca by an anonymous source operating under the pseudonym "John Doe", shamed the rich and famous and took down world leaders.

One of the early casualties was Iceland's Prime Minister Sigmundur Gunnlaugsson, who was forced to resign days after the leaks showed he and his wife owned an offshore company he had not declared when entering parliament.

Then-Pakistani prime minister Nawaz Sharif was also eventually removed from office because of his and his family members' alleged links with offshore companies.

Russian President Vladimir Putin faced enormous political heat (although he has rejected links to offshore accounts and called the leaks part of Western efforts to weaken Russia).

Authorities across the world, including the Australian Taxation Office, moved immediately to investigate potential breaches of the law by their citizens.

And while the ATO has said prosecutions of individuals could take years to eventuate, in the United States federal authorities have already laid charges against several individuals.

The fight for transparency

The Panama Papers renewed global efforts to lift transparency.

Since the leaks, the OECD has been encouraging governments to introduce a register that gives the public free access to the names of people behind secret assets and bank accounts.

Known as a "beneficial ownership register", it would make it harder for criminals to hide who they are and what they get up to.

According to the head of tax at the OECD, Pascal Saint-Amans, this register is the final frontier in fighting tax evasion.

This register was also something that Labor supported in its election pitch, and the former minister for revenue and financial services, Kelly O'Dwyer, said the Government would look at introducing.

In a media release in February 2017, she noted it was a government "commitment" and announced Treasury would consult on how to best introduce a register and report back.

But more than two years on, nothing has happened.

There's been much effort, by those who have a great deal to lose, to fight against anyone who wants to shine a light on murky business deals.

Despite most submissions to Treasury supporting the introduction of such a register, despite the Federal Government's own Black Economy Taskforce calling for it, and despite Australian government agencies including the ATO, the Australian Securities Investments Commission (ASIC) and the Australian Transactions Reports and Analysis Centre all supporting it, the Government has delayed the introduction.

It appears that business and tax lobbyists have had some traction in convincing Liberal ministers that a register is too much red tape.

The person now responsible for hearing their grievances — but who ultimately has the power to see the policy through — is Assistant Minister for Superannuation, Financial Services and Financial Technology, Jane Hume.

A spokesman for Ms Hume said: "The Government is committed to improving the transparency of information around beneficial ownership and control of companies available to relevant authorities … including the establishment of a central register.

"The Government is considering how best to give effect to this commitment while not imposing unnecessary regulation on business."

Why we need a beneficial ownership register

Data leaks of the scale of the Panama Papers and Paradise Papers aren't common, and whistleblowers like "John Doe", who risked his life to out wrongdoing, are a rare breed.

Reporters for German newspaper Suddeutsche Zeitung, Bastian Obermayer and Frederik Obermaier, who received the first batch of documents that sparked the Panama Papers investigation, have themselves noted the rarity of such information.

Obermayer will be in Australia next month.

He will be joining Australian Financial Review journalist Neil Chenoweth and myself in a discussion at The Wheeler Centre about the biggest tax leak in history, and the fallout.

Sorry, this audio has expired The story behind the Panama Papers leak

Ahead of his visit, I asked Obermayer his view about a beneficial ownership register.

"A truly transparent company register should be considered necessary and even normal in a democratic society," he said.

It would not only reduce the incentive for people to evade taxes, but also help target terrorism financiers, arms smugglers and other criminals who are using front companies to hide their murky businesses, he said.

"The only reason not to do a beneficial ownership register is, in my understanding, that the finance lobby is stronger than it should be in our societies," he said.

UN report calls for change

Ms Hume might also want to take note of a review released this month, which looked at the Australian Government's compliance with the United Nations Convention Against Corruption.

This UN review made a number of recommendations for the Federal Government to improve its record of fighting corruption, including introducing a beneficial ownership register.

The Uniting Church and Tax Justice Network's Mark Zirnsak, who made a submission to the UN review as well as numerous inquiries into tax avoidance, has also called on the Government to make the public register a reality now.

"We do not need further delay," he said.

"We need to end the current shell game criminals can play with company ownership."

Mr Zirnsak said it was far too easy to use a false name to set up a front company with dummy directors, and that these had been used in Australia for the purpose of fraud, tax evasion and laundering money.

"These activities do real harm to people, communities and businesses, both here and overseas," he said.

"A public register of real company ownership would make the job of banks easier to detect criminal money and report it to police, by knowing who is really shifting money around."

The pressure is on the Federal Government to move sooner than later to introduce a public register of beneficial ownership that reveals those who have something to hide.