This is what the most expensive U.S. presidential election in history looks like.

The 2012 presidential campaign last week passed the $2 billion mark.

Who is sponsoring all those ads? That’s the catch: We don’t fully know.

Thanks to the Supreme Court’s ruling in the Citizens United case, corporate political spending has no limits. The way the Supreme Court saw it, that unlimited spending would be accompanied by unprecedented transparency. Justice Anthony Kennedy wrote in that decision, “With the advent of the Internet, prompt disclosure of expenditures can provide shareholders and citizens with the information needed to hold corporations and elected officials accountable.”

Only that didn’t happen.

The push-pull between campaign finance accountability and the First Amendment to finance public speech is decades old. There are important values on each side.

We respect that citizens and corporations have the right to express political opinions (and are willing to put their money where their mouth is). But we also feel it is reasonable for voters to know who’s funding the messages.

After all, free speech is not necessarily free.

Just about the same time as the Citizens United ruling, special-interest groups started organizing under a tax code that allows donors to remain anonymous.

The 501(c)(4) designation is for groups whose intended purpose and focus is something other than politics — a union, for instance, or a chamber of commerce. Because their donors might be giving for reasons other than politics, the identities of these groups’ donors may be secret.

This glaring loophole was a factor in the 2010 election, and politicians vowed to change it.

That didn’t happen, either.

The Disclose Act of 2012 failed to win Senate support this summer. So now political mudslinging is in full force, the half-truths are flowing like water and no one knows who is behind much of the advertising.

Big money can create a quid pro quo corruption in which candidates feel beholden to the interests that touted their campaigns. Knowing what those interests are would help us hold elected officials accountable.

The way the system is set up, there’s nothing to prevent foreign interests from fueling ads to directly influence U.S. elections.

Congress must get back to the Disclose Act of 2012, or something like it, to fix the lack of transparency in campaign spending.

— Telegraph Herald (Iowa)