Ads and mailers attacking candidates for public office are flying as thick as fall leaves as the Nov. 2 election approaches. Sorting through the claims and counter-claims can be confusing. But, at least in Oregon, voters can find out who is paying for the ads, because Oregon law requires strict disclosure of political spending. At the national level, that's no longer true.

Ads and mailers attacking candidates for public office are flying as thick as fall leaves as the Nov. 2 election approaches. Sorting through the claims and counter-claims can be confusing. But, at least in Oregon, voters can find out who is paying for the ads, because Oregon law requires strict disclosure of political spending. At the national level, that's no longer true.

This election features a new twist on independent expenditures by groups not connected to a candidate or political party but designed to affect the fortunes of specific candidates.

The U.S. Supreme Court's ruling in the Citizens United case said for the first time that corporations and unions have the same right of free speech under the First Amendment as individuals do, and that limiting their political spending is therefore unconstitutional.

In the past, corporations could not spend money from their general treasuries on political activity; they could spend only money raised by their political action committees from employees (or members, in the case of unions).

That limitation no longer applies. The Nov. 2 election is the first test of this wide-open policy, and so-called "Super PACs" have sprung up to take advantage of it.

As of Wednesday, these "Independent Expenditure Only" groups had spent $259 million on political ads, mailers and other activity.

There is an argument to be made that this is not in itself a bad thing. If our nation values free speech, and if political spending is speech, more speech must be better than less speech.

The problem is, the voting public doesn't know, and in most cases cannot find out, who is doing the speaking.

Nothing in the court decision prohibits rules requiring public disclosure of who is giving money and how much; in fact, the court supported disclosure, saying it would help voters evaluate the arguments made in independent political ads.

It is up to Congress, however, to require disclosure. Senate Republicans blocked a bill that would have done that in time for this election season.

The result is, most of the people and corporations who gave that $259 million did so in secret. Secret, that is, from the American people.

Rest assured, the identities of the contributors won't be a secret to the politicians who wind up getting elected with their help. The givers will be more than willing to reveal themselves and explain exactly what they expect in return for their generosity.

Congress must act to require Super PACs to disclose their donors before the next election. And the American public must demand that it do so.