Published in the San Jose Mercury News and Palo Alto Daily News.

By Anna G. Eshoo (D-Palo Alto)

Two years ago, the Supreme Court's Citizens United decision cast aside a century of precedent and dealt a serious blow to our electoral process. In a shocking 5-4 decision, the court held that corporations and unions were entitled to the same First Amendment rights as people -- a ridiculous notion that Justice John Paul Stevens wisely called "a rejection of the common sense of the American people."

Congress should pass a constitutional amendment to override Citizens United, but that could take years. In the near term, there's one critical tool to fight back: full disclosure. Even the author of the Citizens United decision, Justice Anthony Kennedy, described the importance of transparency in our political system, saying it "permits citizens and shareholders to react to the speech of corporate entities in a proper way."

On the heels of that decision, with my full support, Congress attempted comprehensive legislation called the DISCLOSE Act, which prohibited foreign influence in federal elections, banned government contractors from political expenditures and established requirements for election spending. The DISCLOSE Act passed the House, but unfortunately fell short in the Senate.

After the DISCLOSE Act failed, I led more than 60 of my House Democratic colleagues in calling on President Barack Obama to issue an executive order requiring every company that does business with the federal government to fully disclose its political contributions. With federal contract spending totaling more than $500 billion each year, and roughly one-quarter of all Americans employed by a firm doing business with the government, my proposal would be a major victory for reform, making transparency the norm rather than the exception.

I've taken to the floor of the House repeatedly over the last year offering amendments to secure this critical disclosure, only to have them blocked from consideration each time at the behest of powerful business and lobbying groups. But the president can do it on his own.

Through its 2010 ruling, the Supreme Court blessed the rise of the super PAC. Using undisclosed money from corporations, unions and wealthy individuals, super PACs can deluge voters with unaccountable ads and manipulate electoral outcomes. In the 2010 campaign cycle, super PACs spent more than $135 million on campaigns. According to the nonpartisan watchdog Democracy 21, super PACs and related groups will spend hundreds of millions of dollars in the 2012 election. The sources of this money will never be fully known, to the detriment of every single voter.

The threat of undue corporate influence over America's political system is neither idle nor new. In 1905, President Teddy Roosevelt demanded campaign finance reform. He signed the Tillman Act banning corporate contributions in 1907 and the first disclosure rules in 1910. Since that time, Congress has repeatedly supported a ban on anonymous and unlimited campaign spending, culminating in the landmark McCain-Feingold law in 2002, which I was proud to support.

Californians already know the power of disclosure. During the campaign on Proposition 23, a ballot initiative to roll back greenhouse gas emissions rules, advertisers had to disclose their sponsors. When voters learned that major oil companies were funding the entire campaign, the proposition was overwhelmingly rejected.

Sunlight is the best disinfectant, and two years after Citizens United, disclosure remains the best available weapon to combat the corrosive effects of the court's decision. Corporations aren't people, and shouldn't be treated like them. The president must use his authority and issue the long-awaited executive order straight away. Disclosure puts voters in the driver's seat, and it's time to hand over the keys.