The rules, called Basel Endgame, are the result of more than a decade of efforts by global bank regulators to harmonize patchwork rules that had sprouted up over decades and were further balkanized in varying responses to the 2008 crisis. Michael Barr, the Fed’s top cop, says that even 15 years later, U.S. banks still aren’t prepared for a financial shock.

The government says banks would have to hold about 20% more capital — a buffer they’d build up by socking away profits that might otherwise go to shareholders, employees, or acquisitions. The banks say those numbers are off and have produced their own analysis that puts the add-on closer to 30%.

“As a matter of legal process, it’s not going to be enough to say that a bunch of regulators got together in Switzerland, and this rule is what they brought down from the mountain,” Scalia told Semafor.

“The agencies have to do their own work, explaining why these new requirements are properly calibrated, and why their benefits are worth the costs,” he said. “This proposal doesn’t do that.”

Even using the more conservative figures, a bank with $1 trillion of loans and trading assets in a mix similar to JPMorgan’s would need an extra $20 billion or so of capital, according to a Semafor analysis. Most of that comes from surcharges to mortgages, credit cards, and securities.

“Requiring more capital will almost always improve the stability of the banking system,” said Randy Quarles, the Fed’s chief bank supervisor during the Trump administration. “But it may not improve the stability of the financial system as a whole.” A lot of lending has already been pushed out of banks and into private investment firms, where the Fed has a harder time seeing it, he said.

The proposal has critics even within the government. Two members of the Fed’s board voted against it, as did two members of the FDIC’s board, one of whom said last week that he was “unable to defend or even understand important aspects.”

That leaves Fed Chair Jerome Powell as referee, and he has hinted both in dry government-speak in public and in more pointed comments in private meetings with congressional lawmakers that the proposal is likely to be reworked. He only has a few months to do so: The Fed generally doesn’t announce overhauls on the eve of a presidential election.