Thursday’s U.S. Supreme Court ruling lets corporations, unions and interest groups spend on ads for or against candidates without making financial disclosures. Some corporations, including at least two in Louisiana, have decided to voluntarily report to the public their political expenditures nonetheless.

Well in advance of this week’s decision, the Center for Political Accountability had been pushing for corporations to adopt disclosure and board oversight rules to govern political spending. As of Thursday, the center listed 70 companies agreeing to the disclosures, 50 of which are on the influential S&P 100 index.

Companies operating or based in Louisiana who are on that list include Entergy and Chevron.

Both companies have lobbying arms, the Chevron Employees Political Action Committee and the Entergy Corporation Political Action Committee, that have been giving to candidates for years. Although  these companies now can  run ads attacking candidates who don’t reflect their agenda, or promoting those who do, they still cannot give money directly to candidates. To do that corporations always could and do rely on their PACs.

In the current race for Sen. David Vitter’s seat, the Chevron PAC has given $10,000 to the incumbent through 2009. The Entergy PAC gave $3,000 to Vitter. In the same year, the Chevron PAC gave $4,500 to Rep. Charles Melancon, who’s running against Vitter, while Entergy’s PAC has given him $10,000. Both candidates have raised roughly $655,000 from PACs.