Psst. Maybe you can tell me how much money the big banks give to all these think tanks. Photographer: Andrew Harrer/Bloomberg
Psst. Maybe you can tell me how much money the big banks give to all these think tanks. Photographer: Andrew Harrer/Bloomberg

Whatever else you might say about Massachusetts Senator Elizabeth Warren, she has never been reluctant to take on the rich, the powerful or those who've avoided being held accountable for their role in the financial crisis. The latest example: a letter she sent this week to the heads of the six major too-big-to-fail banks asking them to disclose how much they give to think tanks.

As you know, your institutions are free to express your views to lawmakers and regulators through your lobbying efforts and those of the trade associations that represent you. But the law requires that there be transparency around your direct efforts to influence policymaking through lobbying, with disclosure about your lobbying expenditures. Under current law, however, your institutions are permitted to make financial contributions to think tanks without similar public disclosure. This means you can make enormous contributions that threaten both the independence and public credibility of the work of think tanks out of public view.

This is all fine and dandy, though no one should have very high expectations that the banks will voluntarily offer a tally of the money they give to research organizations. That's why Warren should go all-out and press for rule changes so that think tanks disclose how for-profit companies use their checkbooks to influence public policy.

Think tanks have proliferated, and the political left, right and center all have their idea factories spitting out policy prescriptions. Most are nonprofit organizations, supported mainly by donations.

Those donors get a tax break for their contributions. In other words, the public is subsidizing the giving. In turn, because most research groups pay little or no federal income tax, a subsidy accrues to them, too. What's more, though nonprofits do have to disclose the names of donors to the Internal Revenue Service, that information is withheld from the public.

Of course, there is a great deal to be said for subsidizing the vital work done by many nonprofits, which range from religious groups to universities to hospitals. There's no compelling reason they should have to reveal their donor lists.

Think tanks, though, don't provide spiritual solace, school the next generation or care for the sick.

So what do they offer? In theory, they enrich the conversation about public policy, thus contributing to the social welfare -- one of the tests for determining whether something deserves a nonprofit designation. But what if they're offering nothing more than paid speech? That seems to be what Warren is getting at.

If it is, a disclosure campaign might fit nicely with some proposals the Barack Obama administration is considering to change the status of tax-exempt organizations engaged in political work. The idea is to get a handle on groups such as Crossroads GPS, an organization founded by Republican strategist Karl Rove, and craft rules that clearly define limits on their political activity or make them register as political action committees (which might be what they really are).

As for Warren, her motives seem admirable: enhancing transparency. Her detractors -- Republicans and some fellow Democrats -- see her as trying to settle political scores.

Maybe it really was a coincidence, but Warren sent her letter two days after the Wall Street Journal published an op-ed by Jon Cowan and Jim Kessler, president and senior vice president for policy, respectively, at a think tank called Third Way, which according to its website, "represents Americans in the 'vital center' -- those who believe in pragmatic solutions and principled compromise, but who too often are ignored in Washington." Make that the vital center of the Democratic Party establishment, judging by the roster of people it bills as "Honorary Co-Chairs." Among the honored, Congressmen John Dingell and James Clyburn and Senators Claire McCaskill and Mark Udall.

The op-ed, titled "Economic Populism Is a Dead End for Democrats" was a catalog of woes that will befall the party if Democrats follow Warren and New York City Mayor-elect Bill de Blasio "over the populist cliff."

Getting even may be what Warren has in mind. But does it really matter? If she also is able to shine some light on America's think tanks, it might be a plus for the rest of us, too.

(James Greiff is a Bloomberg View editorial board member. Follow him on Twitter.)