In a series of high-minded-sounding pronouncements, Twitter CEO Jack Dorsey announced in October that his platform would ban all political ads: “We made the decision to stop all political advertising on Twitter globally,” Dorsey tweeted. “We believe political message reach should be earned, not bought,” adding, “Internet political ads present entirely new challenges to civic discourse,” he argued, including “unchecked misleading information” and “deep fakes.”

At the time, Dorsey claimed Twitter was banning not only “candidate ads” but also “issue ads” because “it isn’t fair for everyone but candidates to buy ads for issues they want to push. So, we’re stopping those too.”

Dorsey’s initial ban (announced the same week that Facebook issued its quarterly earnings) was a direct response to Facebook’s announcement that it would not ban political ads–even ones that were untrue. Facebook’s decision prompted Sen. Elizabeth Warren to troll the company by purchasing ads that claimed CEO Mark Zuckerberg was supporting Trump’s reelection. She further unleashed a scolding tweet-storm calling Facebook a “disinformation-for-profit” machine.

(It’s not just principle that’s driving the left’s recent turn against Facebook; many Democrats are worried about how much money Trump’s reelection campaign has been spending on Facebook ads, including many ads related to impeachment, and their likely impact on voters).

Dorsey clearly wished to contrast his company with Facebook, and he received praise from many on the left for doing so, though Twitter has yet to bow to demands from progressives to ban President Trump from the platform for violating Twitter’s rules about bullying.

But they might have been premature in their praise. In its recent clarification of its new ad policy, Twitter retreated from Dorsey’s initial claims and announced that it would allow non-profit organizations, corporations, and individuals to purchase issue ads on the platform, albeit with vague restrictions. Among them, ads “should not have the primary goal of driving political, judicial, legislative, or regulatory outcomes.” Twitter will also allow ads that “call for people to take action in connection with civic engagement, economic growth, environmental stewardship, or social equity causes.”

But who will determine whether an ad is promoting political outcomes? “This is entirely new terrain,” Vijaya Gadde of Twitter told Recode. It is new terrain, but, thus far, the company has been less than forthcoming about the procedures it will use to determine an ad’s legitimacy. Gadde would only say that the company was “prepared that we’re going to make some mistakes, and we’re going to have to learn and improve this policy over time.” In other words: Twitter will decide what constitutes political speech on its platform, and it’s not projecting confidence that it will do so fairly.

One thing Twitter has promised to do is prevent groups who buy ads to micro-target those ads to Twitter users based on political preferences. “We very much believe that cause-based advertising has value, and can help drive public conversation around important topics,” Del Harvey, Twitter’s vice president of trust and safety told the New York Times. “But we still don’t think it should be used with the sort of primary goal of driving political or judicial or legislative or regulatory outcomes.”

It’s a nice idea, although not one that is likely to make a difference in the cesspool that is political Twitter. As Pew Research has noted, people who strongly disapprove of Trump generate “80 percent of all tweets from U.S. adults and 72 percent of tweets mentioning national politics,” compared to those who strongly approve of Trump, who produce only 11 percent of all tweets from U.S. adults.” As well, Pew notes, “taken together, strong disapprovers and strong approvers of Trump generate 97 percent of all tweets mentioning national political from U.S. adults on Twitter.” Extremists, particularly extremist Trump-haters, rule Twitter.

Unlike other Big Tech CEOs, Dorsey has admitted that, although he believes the platform he created isn’t politically biased, “We have a lot of conservative-leaning folks in the company as well, and to be honest, they don’t feel safe to express their opinions at the company. . . They do feel silenced by just the general swirl of what they perceive to be the broader percentage of leanings within the company, and I don’t think that’s fair or right.”

And even though Trump himself uses the platform to great effect, conservatives’ fears about Silicon Valley’s bias aren’t entirely unfounded, although recent efforts to hold hearings to highlight bias, as well as Trump’s “social media summit” at the White House, both fell flat.

The real problem with political speech on social media platforms isn’t bias; it’s the lack of transparency about how these companies make decisions to ban or restrict users’ speech. This problem will plague Twitter as it attempts to implement its new political ad guidelines later this week, and neither conservatives nor liberals should want decisions about political speech in the hands of Silicon Valley engineers, however neutral they claim to be.

Speech, particularly on social media platforms, can be ugly and empowering, misinformed and insightful, hostile or kind. Private companies have every right to determine the speech they will allow on their platforms, and users who don’t like what they see are free to leave those platforms. But as its past and present confusion over political speech suggests, Twitter shouldn’t be in the business of trying to regulate or ban it.