Most campaign money, after all, comes in smaller chunks from individual donors. People who gave $3 to Barack Obama’s presidential campaign in 2008 could not have reasonably expected that their small contributions would influence the future president. Even those who give larger sums rarely contribute the maximum allowed by law, as might be expected of someone trying to buy influence. Instead, individual contributions have increased over time merely in proportion to personal income. Excepting lower-income families, who rarely give to campaigns, Americans from the upper-middle class on up give approximately the same percentage of their income, about 0.04 percent, according to Ansolabehere’s research, to politicians and political groups. Corporations also spend relatively little, and their spending has not increased substantially in recent years. “If companies thought they could just buy politicians,” said Timothy Groseclose, an economics professor at George Mason University, “we should see much more money being spent there.”

In reality, examples like the Massey Energy case are rare. And in 2009, the Supreme Court ordered the West Virginia courts to reconsider its verdict. That year, Blankenship told Adam Liptak of The Times, “I’ve been around West Virginia long enough to know that politicians don’t stay bought.” Justice Anthony Kennedy noted in his Citizens United opinion that 100,000 pages of briefs had not included a single clear example of a quid pro quo purchase of a lawmaker’s vote.

One reason is that buying elections is economically inefficient. Most voters, like most consumers, have defined preferences that are difficult for advertisers to shift. Chevron spent roughly $3 million during a recent campaign backing, certain City Council candidates in Richmond, Calif., where it operates a major refinery. Voters instead chose a slate of candidates who want to raise taxes. “Campaign spending has an extremely small impact on election outcomes, regardless of who does the spending,” the University of Chicago economist Steven Levitt concluded in a 1994 paper. He found that spending an extra $100,000 in a House race might be expected to increase a candidate’s vote total by about 0.33 percentage points. Investors appear to agree that companies can’t make money by investing in political campaigns. A 2004 study found that changes in campaign-finance laws had no discernible impact on the share prices of companies that made donations.

The low level of campaign spending, however, may obscure the real power of wealthy individuals and corporations. Michael Munger, a professor of political science at Duke University, told me that companies are mostly satisfied with the status quo, so they behave more like firefighters than like police officers. Instead of getting involved in each campaign, in other words, they sit back and wait for an alarm to ring. “Incumbents and large corporations can basically spend as much as it would take to defeat some change that would harm them,” he said. “And most of the time that is zero. But the potential is basically infinite.” They spend around 10 times as much on lobbying, suggesting that it’s less effective to influence the selection of policy makers than to influence the policy-making process itself. “If you can give a key piece of information to a politician,” Groseclose told me, “that seems to be more valuable than a campaign contribution.”