A federal district judge in Virginia, James Cacheris, has held that the federal law banning direct corporate contributions to candidates violates the First Amendment, in light of the Supreme Court's controversial Citizens United decision, which struck down federal restrictions on so-called "indepedent" corporate expenditures. The relevant analysis starts at page 42 of the court's decision. Here's the key passage:
This Court recognizes that it must strive to avoid rendering constitutional rulings except where absolutelynecessary. Ashwander v. Tenn. Valley Auth., 297 U.S. 288, 347 (1936). But for better or worse, Citizens United held that there is no distinction between an individual and a corporation with respect to political speech. Thus, if an individual can make direct contributions within FECA’s limits, a corporation cannot be banned from doing the same thing. So because individuals can directly contribute to federal electioncampaigns within FECA’s limits, and because [the corporation contributions ban in 2 U.S.C.] § 441b(a) does not allow corporations to do the same, § 441b(a) is unconstitutional.
So, "for better or worse," this judge felt that he had no choice. The Supreme Court made him do it. Go read FEC v. Beaumont, 539 U.S. 146 (2003), and ask yourself whether you would have lacked discretion to come out the other way. The ban on direct corporate contributions struck down by Judge Cacheris has been in federal law since 1907.