This week, a unanimous federal appeals court struck a small but telling blow for privacy, free speech and accurate campaign disclosure. In Van Hollen v. Federal Election Commission, the lower court had ruled that organizations making electioneering communications -- broadcast communications that merely mention a candidate's name within 60 days before a general election -- must disclose information on all of their donors, even those unconnected to the ads in question. The FEC's regulation had previously required public disclosure only of donors who had paid for particular communications.

As a result of today's ruling, organizations can mention candidates in the coming weeks without being forced to disclose their entire donor lists. This is an improvement: Until today, groups that merely mentioned a candidate -- for example, an ad that says "We stand with our President" -- were required to disclose information on all of their donors. However, if a group ran an ad explicitly saying to vote for or against a candidate -- for example, "The President's policy in the Middle East has failed. Vote for new leadership this fall" -- the group could keep its donors' privacy intact.

The ruling thus helps preserve long-standing rights to donor privacy, which were won in a series of court battles in the 1950s and 1960s by civil rights organizations. In those days, governments sought to force public revelation of donors to the NAACP and other civil rights organizations, exposing them to threats and harassment. In a series of decisions -- most notably NAACP v. Alabama -- the Supreme Court ruled that such nonprofits had a right to keep their donors' names private.

Today, few groups face the same level of harassment as NAACP donors in the deep South might have faced in the 1950s. But donors do face harassment, both official and private. For example, after Proposition 8 passed in California, disallowing same-sex marriage, numerous businesses were boycotted, often merely because one of their employees had contributed to the traditional marriage side of the debate. Many of these employees were fired or forced to resign. Others had their property vandalized.

In 2004, a number of political donors found their names on the website of a group identified by the FBI as a terrorist organization. Their "offense"? They worked for employers who did business with a company that the terrorist group didn't like. They were listed, with their home addresses, on the website, under the headline "now you know where to find them." The FBI determined that the terrorist organization had gotten their addresses and employer information from the public disclosure required by the federal government of campaign donors.

Many groups and individuals are being placed under severe pressure and threats, both official and unofficial, apparently based on their political spending. Indeed, it is perhaps no coincidence that the plaintiff in this lawsuit, seeking more information on donors, is Rep. Chris Van Hollen, D-Md., chairman of the Democratic Congressional Campaign Committee. He has been trying (unsuccessfully) to get Congress to pass the highly partisan DISCLOSE Act, billed by supporters as having a "deterrent effect" on speech hostile to Democrats.

The new ruling is a victory for more accurate and effective disclosure. Under the regulations reinstated by the Court of Appeals, the public knows which organizations or entities are paying for every electioneering communication. But the lower court's ruling actually required nonprofits making electioneering communications to disclose, as "paying" for the ad, members who might have had nothing to do with the ad and may even have disagreed with the decision to run it. This only confuses, rather than enlightens, the public and leads to confusion about how much is spent. Disclosures for each ad would have had to list all the members of the group and their donations, meaning the same donations would be reported over and over as paying for many ads.

Thus, while the Court of Appeals decision may seem like inside baseball, in fact, it is a small but important victory for free speech and for reasonable, accurate political disclosure rules.

Mr. Dickerson is director of litigation at the Center for Competitive Politics. Mr. Smith is a former chairman of the Federal Election Commission, a professor of law at Capital University and the center's chairman.