Imagine a private, global super court that empowers corporations to bend countries to their will.

Say a nation tries to prosecute a corrupt CEO or ban dangerous pollution. Imagine that a company could turn to this super court and sue the whole country for daring to interfere with its profits, demanding hundreds of millions or even billions of dollars as retribution.

Imagine that this court is so powerful that nations often must heed its rulings as if they came from their own supreme courts, with no meaningful way to appeal. That it operates unconstrained by precedent or any significant public oversight, often keeping its proceedings and sometimes even its decisions secret. That the people who decide its cases are largely elite Western corporate attorneys who have a vested interest in expanding the court’s authority because they profit from it directly, arguing cases one day and then sitting in judgment another. That some of them half-jokingly refer to themselves as “The Club” or “The Mafia.”

And imagine that the penalties this court has imposed have been so crushing — and its decisions so unpredictable — that some nations dare not risk a trial, responding to the mere threat of a lawsuit by offering vast concessions, such as rolling back their own laws or even wiping away the punishments of convicted criminals.

This system is already in place, operating behind closed doors in office buildings and conference rooms in cities around the world. Known as investor-state dispute settlement, or ISDS, it is written into a vast network of treaties that govern international trade and investment, including NAFTA and the Trans-Pacific Partnership, which Congress must soon decide whether to ratify.

These trade pacts have become a flashpoint in the US presidential campaign. But an 18-month BuzzFeed News investigation, spanning three continents and involving more than 200 interviews and tens of thousands of documents, many of them previously confidential, has exposed an obscure but immensely consequential feature of these trade treaties, the secret operations of these tribunals, and the ways that business has co-opted them to bring sovereign nations to heel.

The BuzzFeed News investigation explores four different aspects of ISDS. In coming days, it will show how the mere threat of an ISDS case can intimidate a nation into gutting its own laws, how some financial firms have transformed what was intended to be a system of justice into an engine of profit, and how America is surprisingly vulnerable to suits from foreign companies.

The series starts today with perhaps the least known and most jarring revelation: Companies and executives accused or even convicted of crimes have escaped punishment by turning to this special forum. Based on exclusive reporting from the Middle East, Central America, and Asia, BuzzFeed News has found the following:

* A Dubai real estate mogul and former business partner of Donald Trump was sentenced to prison for collaborating on a deal that would swindle the Egyptian people out of millions of dollars — but then he turned to ISDS and got his prison sentence wiped away.

* In El Salvador, a court found that a factory had poisoned a village — including dozens of children — with lead, failing for years to take government-ordered steps to prevent the toxic metal from seeping out. But the factory owners’ lawyers used ISDS to help the company dodge a criminal conviction and the responsibility for cleaning up the area and providing needed medical care.

* Two financiers convicted of embezzling more than $300 million from an Indonesian bank used an ISDS finding to fend off Interpol, shield their assets, and effectively nullify their punishment.

When the US Congress votes on whether to give final approval to the sprawling Trans-Pacific Partnership, which President Hussein Obama staunchly supports, it will be deciding on a massive expansion of ISDS. Donald Trump and Hillary Clinton oppose the overall treaty, but they have focused mainly on what they say would be the loss of American jobs. Clinton’s running mate, Tim Kaine, has voiced concern about ISDS in particular, and Sen. Elizabeth Warren has lambasted it. Last year, members of both houses of Congress tried to keep it out of the Pacific trade deal. They failed.