With corporate political spending–some of it secret–expected to explode in the 2012 election cycle, a group of law professors is petitioning the U.S. Securities and Exchange Commission (SEC) to make a formal policy requiring corporations to disclose such expenditures to shareholders and the public.

“Disclosure of corporate political spending is necessary not only because shareholders are interested in receiving such information, but also because such information is necessary for corporate accountability and oversight mechanisms to work,” reads the petition, which is headed by Lucian A. Bebchuk of Harvard Law School and Robert J. Jackson, Jr of Columbia Law School.

The document points out that in the U.S. Supreme Court’s recent decision, Citizens United v. FEC, the Supreme Court cited examples of shareholders holding their corporations accountable for its political speech. “For this mechanism to work, however, shareholders must have information about the company’s political speech…”

While corporations must report some types of political spending, thanks to recent legal developments, more of this spending is becoming opaque. What we do know about spending is scattered among federal agencies–mainly the U.S. Federal Election Commission (FEC) and the Internal Revenue Service. Requiring corporations to report their spending in one spot, on their websites, would create a "one stop shop" for the public to glean such information.

The push to get corporations to disclose their political political activities has gained steam recently thanks to the recent U.S. Supreme Court decision in Citizens United v. FEC, which opened the door to unlimited contributions by unions and corporations to influence elections.

That, combined with other recent decisions, has created an environment where certain groups that are not required to disclose their donors have been increasing their spending in the political arena. (You can look up what we do know about spending on issue ads and independent expenditures using this “Follow the unlimited money” tracker here.)

Last summer, Congressional Republicans rejected the DISCLOSE Act, which would have required more corporate disclosure of political contributions—legislation that the Sunlight Foundation supported.

The 2010 elections saw an explosion of spending by so-called 501(c)(4) organizations—otherwise nonprofit groups that may engage in some political activity—which are not required to report their donors. "Super PACs," groups that can raise and spend unlimited amounts of money on running campaign ads, were also created.

Already, many of these organizations have begun raising money for the 2012 elections. “There’s going to be tremendous pressure to start sending money through c(4)s,” says Bruce Freed, president of the Center for Public Accountability (CPA), an organization that advocates for transparency in corporate political spending.

The eight-year-old organization has pushed for corporations to disclose such spending voluntarily, with some success. But a look at these disclosures shows how much we still don't know.

For example, in 2010, during the thick of the debate over the Dodd-Frank financial reform law and its immediate aftermath, the nation’s tenth largest bank, U.S. Bancorp, voluntarily reported spending nearly $700,000 in dues to trade associations such as the Financial Services Roundtable and the American Bankers Association that in turn used such funds to help run their huge lobbying operations.

There is no legal requirement that companies publicly report their contributions to such trade associations–which typically are organized under the 501(c)(6) section of the tax code. Only 45 major companies voluntarily disclose their payments to trade associations, according to a database maintained by CPA.

According to a recent analysis by Baruch College of New York, which rated corporations on the level of their political disclosure, only 22 percent of S&P 100 companies voluntarily publicly disclose their political spending, and on average, those companies that contribute the most disclose less. CPA is preparing its own index report, which will be released in October.

The mega-bank Bank of America (BOA) does not disclose political activity it is not required to report elsewhere. Yet an analysis by CPA points out that public sources show that BOA is a member of such powerful trade association as the Business Roundtable, the American Bankers Association, and the Financial Services Roundtable.

And even when companies have relatively good disclosure policies, there can be big holes. Marriott International has a policy dated June 2011 that says it will disclose a wide range of political activities, including PAC contributions, payments to trade associations, contributions to so-called "527" organizations and independent expenditures. However, the curious shareholder would find no mention on the report that CEO J.W. Marriott and his brother Richard Marriott had given $500,000 apiece to the "Super PAC" formed by GOP presidential candidate Mitt Romney. There is no mention in Marriott policy of contributions to 501(c)(4) organizations, which do not disclose their donors.

Finally, because there is no standardized format for disclosure, companies that do provide information do so in indiosyncratic formats that must be read individually, as opposed to databases or spreadsheets that are easily analyzed.

About the data

What: Corporate campaign contributions

Where: Currently corporations must disclose some of their political spending, but is scattered in different locations. Sunlight Foundation's website, transparencydata.com, gathers much of these data in one place:

• Corporations report their lobbying expenses to the U.S. Secretary of the Senate and Clerk of the House.
• Corporations report honorary contributions made by registered lobbyists to nonprofit groups in honor of lawmakers to the U.S. Secretary of the Senate and Clerk of the House.
• Political Action Committee (PAC) contributions to federal campaigns, which are subject to limits, are reported to the U.S. Federal Election Commission (FEC).
• Individual contributions by corporate executives to campaigns, which are subject to limits, are reported to the FEC.
• Corporate and executive contributions to "Super PACs"–PACs that can take unlimited contributions and make independent expenditures and electioneering communications in elections–report donors to the FEC.
• Corporate and individual contributions to "527"s, political groups that spend on electioneering communications, are reported to the U.S. Internal Revenue Service (IRS).
• Reporting on corporate spending in state elections varies according to state law.
• There is no requirement that corporations publicly report contributions to trade associations, such as the Chamber of Commerce. These groups are organized under 501(c)(6) of tax code.
• There is no requirement that corporations publicly report contributions to organizations organized under section 501(c)(4) of the tax code, which may engage in some political activity.
• The Center for Public Accountability, a nonprofit organization, maintains a database of corporate policies on disclosure of political spending here.

Some corporations voluntarily are making availabile political expenditures on their websites. A group of law school professors has petitioned the U.S. Securities and Exchange Commission (SEC) to set a formal policy regarding such centralized disclosure of all political spending.

Availability:  Some reports are scattered among federal and state agencies. Because centralized disclosure is voluntary, information varies; however companies that do disclose information typically do so on their websites.

Usability: There is no standard for corporations to report political contributions on their websites., so often the information is posted in awkward pdf document format that is not easily analyzed.