Let’s not make excuses for the IRS. The agency shouldn’t have subjected conservative groups to special scrutiny. Campaign finance reform groups should have immediately called for hearings when this scandal broke: Imagine the hue and cry if the IRS during the Bush administration had singled out “progressive” groups for special tax scrutiny and sent them unprecedented questions about their contributors and activities. Given the danger going back to President Richard Nixon of using the IRS against political enemies, the agency has to be scrupulously nonpartisan and fair. Congressional investigations and the Department of Justice criminal investigation announced Tuesday are inevitable and warranted.

But the larger picture here shows why the IRS felt itself forced into the role of campaign finance regulator, and why people also are calling for the Securities and Exchange Commission and state attorneys general to regulate campaign contributions. This is all about the failure of Congress to require the disclosure of donors who bankroll designed to influence elections.