“It’s the biggest leak we’ve ever seen of this kind—it’s like having a tsunami coming your way and the surfboard’s all greased up and ready to go,” says John Christensen, director and co-founder of the UK-based Tax Justice Network, which investigates the offshore wealth industry and each year publishes the Financial Secrecy Index, which estimates that $21 trillion to $32 trillion of private wealth “is located, untaxed or lightly taxed in secrecy jurisdictions around the world.” Panama is among the index’s worst offenders.
For the uninitiated, a tax shelter is a legal way to minimize or decrease a person’s taxable income. For instance, a 401(k) plan is technically a tax shelter. But the legality of some tax-efficient vehicles can be murky, particularly when they are used to illegally conceal the ownership or full extent of a person’s wealth or ties to illicit operations. Avoiding taxes has been a key plank of the world’s wealthy for decades, contributing to the growing wealth gap and placing an ever greater strain on ordinary taxpayers.
“While many people don’t know it, this affects the global economy, the way our governments work, all of us every single working day of our lives,” Christensen says. “The public is losing basic services left, right and center, and at the same time they are being burdened with more taxes because the global elite aren't paying their fair share.”
Among those caught up in the leak were 12 current and former world leaders among 143 politicians and their families, friends and associates, including the King of Saudi Arabia Salman bin Abdulaziz Al Saud; Russian President Vladimir Putin; Ukrainian President Petro Poroshenko; Pakistan’s Prime Minister Nawaz Sharif; Iraqi Vice President and former acting prime minister Ayad Allawi; the family of Chinese President Xi Jinping and current and former members of China’s Politburo.
Also implicated was the former prime minister of Qatar, Hamad bin Jassim bin Jaber Al Thani, and former emir of Qatar, Hamad bin Khalifa Al Thani; cousins of Syrian President Bashar al-Assad, Rami and Hafez Makhlouf; the son of Egypt’s ex-president, Alaa Mubarak; the children of Azerbaijani President Ilham Aliyev. And also Icelandic Prime Minister Sigmundur Davíð Gunnlaugsson, who faced calls for his resignation. By late Monday, politicians in Iceland—the only country to have imprisoned dozens of bankers and financiers in the wake of the 2008 financial crisis—were calling for a vote of no confidence.
In the UK, the late father of Prime Minister David Cameron, Ian Cameron, was also named in the leak, along with six members of the House of Lords, three former Conservative members of Parliament and dozens of donors to British political parties. Downing Street declined to comment Monday. This spring, Cameron plans to hold a global anti-corruption summit in London that’s expected to address issues surrounding tax shelters.
Also on the list were 29 billionaires featured in Forbes Magazine’s list of the world’s 500 richest people and celebrities such as actor Jackie Chan and world-famous footballer Lionel Messi, along with 20 other high-profile sports stars. 
Christensen says that while the Panama law firm at the center of the controversy, Mossack Fonseca, is not well known outside global financial circles, the world’s fourth-largest offshore law firm is “a whale among the firms known for setting up offshore tax shelters,” with offices on nearly every major continent, from the top tax havens of the British Virgin Islands, Gibraltar, Jersey and Zurich to offices across the Americas, Europe, the Middle East and Asia. 
Christensen himself is a former senior civil servant from the island of Jersey who previously worked inside the UK’s global network of overseas territories and Crown dependencies housing offshore wealth, which include Jersey and the British Virgin Islands. Both were implicated in the document leak. 
Since last year, Christensen has worked with the German newspaper, Süddeutsche Zeitung, which obtained the leaked documents from Mossack Fonseca through an anonymous source, sharing them with more than 370 journalists affiliated with the International Consortium of Investigative Journalists (ICIJ) from 107 media organizations in 76 countries, who are still combing through the records for further revelations and are expected to release more details shortly. The ICIJ is the watchdog journalism branch of the Center for Public Integrity, a Washington nonprofit, nonpartisan investigative group. 
The leak is the biggest in history, greater than the cache of documents released by Wikileaks, and contains information from 1977 to December 2015, including the details of 214,000 entities, such as trusts, foundations and shell companies that can be used to hide the true ownership of assets. 
“These law firms are pivotal to creating tax shelters,” Christensen says. “They advise clients and set up the layers of secrecy that allow for the concealment of offshore money. Then they hide behind the attorney-client privilege.”
Most of the documents leaked are emails. Others contain images of contracts, passports and memos, including one from a partner at Mossack Fonseca that stated, “Ninety-five percent of our work coincidentally consists in selling vehicles to avoid taxes.”
In response to the leak, Mossack Fonseca released a lengthy statement reported by Newsweek earlier, explaining it “cannot provide response to questions that pertain to specific matters, as doing so would be a breach of our policies and legal obligation to maintain client confidentiality.” It also indicated that it has never been found guilty of any wrongdoing and the leak may have been the result of a data breach. 
Panama is known for defending what Christensen calls “an extreme secrecy model” that he says is “determined not to engage with the rest of the world in any effort toward financial transparency.”
The country ranks number 13 on the Tax Justice Network’s Financial Secrecy Index, while the U.S. ranks number three after Switzerland and Hong Kong (at number one and number two respectively). The UK comes in at number 15.
In response to questions about the release of additional names from the U.S., the editor of Süddeutsche Zeitung said on Twitter: "Just wait for what is coming next."
Christensen says so far the Panama Papers leak—which is still being mined by the team of journalists—did not contain what he considered to be a “representative” number of U.S. offenders. 
“I do expect to see more scalps, including from Western countries like the U.S.,” Christensen says. “This is likely just the beginning.”