THERE ARE 2.2 million people now incarcerated in American prisons - the most, by far, in any country on this planet. A large number of them are no doubt - or at least beyond a reasonable one - guilty of terrible crimes that have harmed others.

But tens of thousands are imprisoned for much less: for stealing or selling (or possessing) relatively small amounts of drugs, or filing false tax returns or maybe cooking the books of their small businesses. Or because they have incompetent lawyers. Or because they can't make bail.

So, the question raised yet again by the PBS documentary show "Frontline" last week - Why has not one Wall Street titan been indicted by the U.S. Justice Department in connection with the 2008 financial crisis? - must be viewed against that backdrop. With substantial evidence of fraud, not one criminal case could be assembled and taken to trial?

That's Lanny Breuer's story and he's sticking to it. Breuer, chief of the Justice Department's criminal division for four years (according to the Washington Post, he plans to leave soon), told PBS something to the effect of: What happened may look, walk and talk like fraud, but there's no way to really prove that the big shots intended, in their heart of hearts, to commit an actual crime.

Experienced prosecutors think otherwise. But Breuer's excuse is not as disturbing as the notion, expressed publicly by him and others, that - even if there's evidence to make a criminal case - Wall Street banks shouldn't be held accountable for crimes because such prosecutions could destabilize them and thereby upset the financial markets.

The banks are deemed, at least by some in a position to do something about it, "Too Big to Jail" - an idea, by the way, that is as absurd as it is maddening. As William K. Black, who headed the prosecutions in the savings-and-loan scandals during the Reagan administration, put it: "Seriously, you want to keep felons in charge of a bank for bank stability?"

The poster child for "Too Big to Jail" was the $1.9 billion fine assessed last December against the British-based bank HSBC that, for nearly a decade, facilitated money-laundering for the governments of Libya and Iran, as well as for Mexican drug cartels (to the tune of $881 million) that are believed responsible for the deaths of more than 50,000 people. The fine was indeed the largest ever levied on a bank - but compare it to the $17 billion in profits made by HSBC in one year. Besides, the people who pocketed the proceeds from the wrongdoing didn't personally pay the fine or face any other inconveniences.

Not only is this grossly unfair, it all but guarantees that many of these outrages will happen again.

With much fanfare last week, President Obama announced the appointment of Mary Jo White to head the Securities and Exchange Commission, touting her prowess as a prosecutor (even though in recent years she's made beaucoup bucks defending the same people she used to indict).

So, now's as good time a time as any to confront the nonsense that two-bit crooks should face one kind of justice in America while billion-dollar thieves face none at all.