A report issued last week by the minority staff of the Senate Finance Committee details how fallen lobbyist Jack Abramoff exploited tax-exempt organizations, both sham nonprofits and otherwise-legitimate charities, to move money from clients he disdained to congressmen he hoped to influence.

Why were charities Abramoff's go-to vehicles as he sought to transfer funds covertly through Washington's corridors of power? The primary attraction was their opacity, their ability to raise money in any amount, without limit, from any individual or entity anywhere in the world without disclosing the contributors to anyone. This makes good sense for honest charities helping people in need, but Abramoff took advantage of this situation to circumvent campaign-finance laws and congressional ethics rules and provide illicit benefits to powerful politicians.

Though members of Congress are subject to strict rules regarding gifts, travel and entertainment, there have long been exceptions for "value received from charity" — ostensibly to permit officials to help charities raise money for worthy causes. So the tax-exempt treasuries of willing nonprofits such as Americans for Tax Reform, run by the Republican strategist Grover Norquist, became conduits through which funds from lobbyists such as Abramoff and other special interests were transferred to elected officials, their families and their aides in the form of lavish travel, expensive meals, golf outings and tickets to sports and entertainment events.

The rules that govern charitable giving obscured the true source of these gifts, while at the same time affording lobbyists private access to the congressmen they were trying to influence. In its 2003 decision upholding the campaign-finance law, the Supreme Court repeatedly expressed its concern that tax-exempt organizations could be abused in just this way. And now this grim report from the Senate Finance Committee's Democratic investigators should remind Congress and tax-exempt organizations that reform is overdue. The guiding principle should be simple and direct: A politician's only relationship with a charity should be as a contributor. Elected officials should not accept travel, meals or golf-course fees, even if they claim that participating in charity events will induce others to write checks for a good cause.

To put this principle into effect, Congress should begin by eliminating exceptions in ethics rules, campaign-finance laws or lobbyist-registration laws for benefits channeled to politicians through nonprofit, tax-exempt entities. Any funds or benefits that a charity gives to a politician or a political committee should be traced back to the original contributor on regularly filed disclosure reports. Equally important, politicians should be prohibited from raising money from third parties for charities they control, directly or indirectly.

If politicians help other charities raise money, they should accept absolutely nothing in return from those organizations or from any organizations related to them. The same rules should apply to politicians' spouses, their children and their children's spouses, as well as to current and former staff members and their immediate families. Finally, Congress should establish an electronic database in which members must report all their contributions to charities, benefits they receive from charities and their leadership positions in such groups.

As IRS Commissioner Mark Everson noted back in January, when the government announced Abramoff's plea agreement, "The mixing of politics, money and charities is, simply stated, a bad cocktail." Indeed, it's distressing to see that, in exchange for a taste of the high life, members of Congress were apparently selling what cannot be for sale in a representative democracy — access to the public-policy process and possibly even their votes.

Charities serve many indispensable purposes, but financing the livings of the powerful and privileged is not one of them.

Frances R. Hill, a professor of law at the University of Miami in Coral Gables, Fla., is the director of the tax program at the Campaign Legal Center in Washington. She wrote this for The New York Times.