Six years ago today President Bush signed into law the Bipartisan Campaign Reform Act, otherwise known as McCain-Feingold. Sen. McCain, who has all but captured the Republican nomination for president in 2008, does not note the anniversary on his website. Perhaps, like many others, he has come to see the legislation as a mistake. According to his website, Sen. McCain is raising money today in Denver and Salt Lake City. Perhaps someone will ask him about the anniversary of his namesake legislation.

Over the past six years, there has been much debate about BCRA and its consequences. I will not repeat those arguments now; the discussion of a year ago remains relevant.

However, I do see one possible result of BCRA that will not please its sponsoring groups. I have been reading Joseph Cantor and Sam Garrett’s interesting history of efforts to pass taxpayer financing of congressional campaigns. They note that advocates have sought public financing as much to limit overall campaign spending as to prevent corruption. In the presidential system, for example, candidates agree to limit their spending in exchange for public money. If public funding were universal, so the argument goes, spending would be limited.

But candidates have never been the only sources of spending, and after BCRA, individuals and groups have learned how to raise and spend money independently. They have learned to design and manage vehicles for such independent spending. They have created arguments and legal theories to protect such vehicles and such spending from legal sanctions. Who knows? They may even have learned how independent spending can help a candidate without violating the law against coordinating such spending with a campaign.

Even if public financing for Congress passed, those who wish to spend money on campaigns have learned how to do so, voluntary spending limits on candidates notwithstanding. For that reason, it is hard to see how public financing would reduce overall spending.

So incentives established by BCRA have made public financing less likely to succeed on its own terms. I think that counts as an unintended consequence.