To old political hands, wise to the ways of candidates and money, 1972 was a watershed year. Richard M. Nixon’s re-election campaign was awash in cash, secretly donated by corporations and individuals.

Fred Wertheimer, a longtime supporter of campaign finance regulation, was then a lawyer for Common Cause. He vividly recalls the weeks leading up to April 7, 1972, before a new campaign finance law went into effect requiring the disclosure of the names of individual donors. “Contributors,” he said, “were literally flying into Washington with satchels of cash.”...

In this year’s midterm elections, there is no talk of satchels of cash from donors. Nor is there any hint of illegal actions reaching Watergate-like proportions. But the fund-raising practices that earned people convictions in Watergate — giving direct corporate money to a campaign and doing so secretly — are back in a different form in 2010.

This time around, the corporations are still giving secretly, but legally. In 1907, direct corporate donations to candidates were legally barred in a campaign finance reform push by President Theodore Roosevelt. But that law and others — the foundation for many Watergate convictions — are all but obsolete. This is why many supporters of strict campaign finance laws are wringing their hands....