Carl Levin is at it again. His Senate Subcommittee on Permanent Investigations, perhaps the best investigatory panel in Congress, particularly on financial matters, has honed in on JPMorgan Chase and the Fail Whale trades.

JPMorgan Chase & Co.’s wrong-way bets on derivatives are the focus of an escalating investigation by a U.S. Senate panel led by Carl Levin that has grilled executives from banks including Goldman Sachs Group Inc. and HSBC Holdings Plc, three people briefed on the inquiry said.

Levin’s Permanent Subcommittee on Investigations is seeking testimony from those who worked in or helped lead JPMorgan’s chief investment office, according to the people, who asked not to be identified because the inquiry isn’t public. The unit’s London staff lost at least $5.8 billion this year on the botched wagers, which were large enough to shift markets.

So, good news and bad news here. The good news is that Levin and his team really know their chops here. Their investigations against HSBC and Goldman Sachs were comprehensive and detailed, and painted a clear picture of fraud and illegality. The bad news is that the SPSCI is not a prosecuting authority. And we saw exactly what happened the last time, when they put together a dynamite Goldman Sachs report, referred it to the Justice Department, and they… did nothing at all with it.

There is the potential for Levin’s committee to really damage JPMorgan Chase reputationally with a deep-dive investigation. But sadly, it’s not likely to translate into action under the current DoJ. This investigation could take years to germinate, however, so maybe new leadership will strike a different pose, though I wouldn’t be hopeful.

The other piece of this is Levin keeping the pressure on while we await the final writing of the Volcker rule. Levin and Jeff Merkley authored that part of Dodd-Frank in Congress, and they want to see broad restrictions on the type of trading JPMorgan Chase engaged in. So an investigation into malfeasance could sway the regulators to ban certain types of activity, in a perfect world.