In the 2000s, the IRS uncovered a widespread pattern of tax avoidance among the ultra-wealthy, more ubiquitous and intractable than anything it had ever imagined. Something had to be done.

But the discovery alone wasn’t enough to bring down the hammer of justice. And the reasons why tell us a lot about what kind of power we need to build to take on the rich.

The IRS wanted to go after these ultra-wealthy tax cheats, write Jesse Eisinger and Paul Kiel write in a new report in ProPublica, but the agency was badly outmatched. Billionaires had already spent decades developing complex, under-the-radar evasion schemes, and had formidable teams of lawyers and accountants on hand. Those teams were often better-paid and more knowledgeable than the IRS staff themselves.