From the majority opinion:
The law before us is an outright ban, backed by criminal sanctions. Section 441b makes it a felony for all corporations — including nonprofit advocacy corporations — either to expressly advocate the election or defeat of candidates or to broadcast electioneering communications within 30 days of a primary election and 60 days of a general election. Thus, the following acts would all be felonies under §441b: The Sierra Club runs an ad, within the crucial phase of 60 days before the general election, that exhorts the public to disapprove of a Congressman who favors logging in national forests; the National Rifle Association publishes a book urging the public to vote for the challenger because the incumbent U. S. Senator supports a handgun ban; and the American Civil Liberties Union creates a Web site telling the public to vote for a Presidential candidate in light of that candidate’s defense of free speech. These prohibitions are classic examples of censorship.
Section 441b is a ban on corporate speech notwithstanding the fact that a PAC created by a corporation can still speak. A PAC is a separate association from the corporation. So the PAC exemption from §441b’s expenditure ban, §441b(b)(2), does not allow corporations to speak. Even if a PAC could somehow allow a corporation to speak — and it does not — the option to form PACs does not alleviate the First Amendment problems with §441b. PACs are burdensome alternatives; they are expensive to administer and subject to extensive regulations. For example, every PAC must appoint a treasurer, forward donations to the treasurer promptly, keep detailed records of the identities of the persons making donations, preserve receipts for three years, and file an organization statement and report changes to this information within 10 days.
And that is just the beginning. PACs must file detailed monthly reports with the FEC, which are due at different times depending on the type of election that is about to occur: “‘These reports must contain information regarding the amount of cash on hand; the total amount of receipts, detailed by 10 different categories; the identification of each political committee and candidate’s authorized or affiliated committee making contributions, and any persons making loans, providing rebates, refunds, dividends, or interest or any other offset to operating expenditures in an aggregate amount over $200; the total amount of all disbursements, detailed by 12 different categories; the names of all authorized or affiliated committees to whom expenditures aggregating over $200 have been made; persons to whom loan repayments or refunds have been made; the total sum of all contributions, operating expenses, outstanding debts and obligations, and the settlement terms of the retirement of any debt or obligation.’”
PACs have to comply with these regulations just to speak. This might explain why fewer than 2,000 of the millions of corporations in this country have PACs. PACs, furthermore, must exist before they can speak. Given the onerous restrictions, a corporation may not be able to establish a PAC in time to make its views known regarding candidates and issues in a current campaign.