Last week, France embarked on a new frontier of hate speech prosecution: Twitter. Figuring that racist and anti-Semitic tweets are the same as making such remarks on TV—which is banned in the European Union—a French court demanded that Twitter turn over what it knew about users responsible for the offending tweets, so they could be tracked down and prosecuted. Meanwhile, France’s minister of women's rights wants Twitter to develop its own filters that will stop all kinds of hateful remarks from ever emerging in public.

In America, where free speech protections are nearly absolute, we have a different approach to noxious tweets: vigilante justice. In recent months, a number of media outlets have rounded up 140-character gripes from people dismayed over the reelection of a black president, or furious that a black hockey player scored a game-winning goal, or eager to share how the Red Dawn remake really makes them feel about Asians. The blog Jezebel even pursued some of the culprits, publishing whatever biographical details it could find online. The operational theory is a twist on the Twitter-as-truth-machine model that emerged during Hurricane Sandy: Twitter as moral scold, democratically correcting against speech that violates the norms of civil society.

“Because the First Amendment basically takes the prosecution of nearly all speech acts off the table, shaming is becoming a quintessentially American response to offensive speech online,” explains Deen Freelon, an assistant professor at American University’s School of Communications.

So which approach works better? Shouldn't we be able to tell, empirically, whether prosecuting hate speech in court or exposing it to public scrutiny leads to less hate—or at least less hate speech—overall?

Surprisingly, given the resources already devoted to combating racism online, nobody's tried to find the answer. The researchers and advocates I talked to couldn't name a single study that attempts to quantify how people react to having their racist remarks—whether they show up on Twitter or more conventional hate sites—censored outright versus mocked on the Internet.