DEMOCRATIC COPYCATS of Russian disinformation techniques, it seems, did not restrict themselves to one state this past election cycle: Late last year, The Post reported on a project backed by Internet billionaire Reid Hoffman to interfere in Alabama’s 2017 special election for Senate. Now, more information has surfaced on a secret experiment targeting conservative voters in races across the country.

We would hope political committees and campaigns on both sides of the aisle would swear off destructive tactics such as paying for professional trolls or creating inauthentic pages. But the breadth of meddling discovered so far is one more argument for companies and Congress to put controls in place to prevent bad behavior. Those measures should start with advertising.

Facebook requires political advertisers to include disclaimers identifying themselves, which is a good thing — and more than the law mandates. But those disclaimers are not always illuminating: Authorized buyers can insert their own text into the “Paid for by” field, and that text is not accompanied by any identifying information or linked to a page where that information is available. In the latest disinformation case, ads were accurately listed as belonging to “News for Democracy,” but that name was not supplemented by a website or point of contact, and an Internet search turns up nothing immediately clarifying.

Mark Zuckerberg is too successful to be naive about the dangers of Facebook, says tech CEO and activist Anil Dash, who wants the company to invest in a big fix. (Kate Woodsome, Gillian Brockell/The Washington Post)

The Honest Ads Act, which House Democrats have incorporated into their inaugural legislative package, would codify Facebook’s disclaimer practices and expand on them, demanding that digital platforms offer relevant information for the public to be able to track down the real party behind an ad buy. It’s a good start, though lawmakers should craft an exemption for news sites, which have heightened constitutional protections — and on which there has been no documented problem with misleading advertisements. (The Post and other publishers are challenging the constitutionality of a Maryland law passed last year that imposes similar requirements relating to online political ads. A federal judge ruled in January that the law violates the publishers’ First Amendment rights.)

But even stricter ad rules would not entirely solve the problem. News for Democracy crafted pages called “Our Flag Our Country,” “Self-Reliant Republic,” “The Holy Tribune” and more, passing them off as conservative before slipping in Democratic messaging. These pages were listed as news companies and disclosed nothing but their names. This practice would have been misleading even if the backers of ads for those pages were identified fully.

Congress could legislate more granularity in reporting online expenditures, asking campaigns and outside groups to indicate, for example, whether they have bought up bots or hired consultants to manufacture Internet communities. But lawmakers cannot tell a platform such as Facebook to disclose who is behind every political page or group. Companies will have to do that voluntarily, mandating that publishers reveal their origins and provide contact information for their administrators.

The Democratic disinformation debacle exposes another facet of politics’ dark-money problem. Even now, it is unclear where exactly News for Democracy came from or who besides Mr. Hoffman supported it. Platforms can make dark money darker still, or they can shed a little light.

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