The identification of political ads on Facebook often goes wrong

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© Joris Snaet

© Joris Snaet

Researchers at KU Leuven (belonging to the imec-DistriNet research group) and New York University (Cybersecurity for Democracy) have demonstrated that on a global scale, Facebook misjudges up to 83 percent of ads that they or the researchers deemed political. In some cases, Facebook does not recognise them as political ads, while they often wrongfully label non-political ads as political.

It is in the US and New Zealand that Facebook achieved the most success in filtering ads correctly. In those countries, only one percent of ads slip through the net, even though in the US, the number of ads involved still amounts to just under ten thousand. Facebook achieved its worst score in Malaysia, where 45 percent of ads remain under the radar. Belgium is situated in between, at position 28 of the 58 countries surveyed, at almost nine percent.

"Facebook failed to detect undeclared political ads of almost any Belgian political party," says Victor Le Pochat, PhD researcher at imec-DistriNet (KU Leuven) and holder of a PhD fellowship from the FWO. "On a worldwide level, Facebook was very poor at distinguishing political ads from non-political ads. This ultimately misleads both users and advertisers on Facebook: either it is unclear that an ad is actually conveying a political message, or ads are wrongly removed because Facebook believes they are political."

Political ads Facebook developed its own rules for "ads about social issues, elections or politics" in 2018. The Brexit referendum and the 2016 US election earned the social network much criticism about the way in which biased information or erroneous reporting was allowed to run rampant. Since then, Facebook requires political ads to be labelled in order to indicate who is paying for them. Facebook primarily relies on civic-mindedness and expects advertisers themselves to indicate whether their ads are about social issues, elections or politics. Not all advertisers do that, however. An algorithm then tries to identify ads that have not been declared. With varying degrees of success, as this study shows.

Facebook could take some simple measures to improve its detection of political ads, but it has already indicated that it doesn’t feel particularly inclined to do so.


The shortcomings of screening are causing harm on two levels. On the one hand, we have the false negatives - political ads that are not recognised as such. These not only undermine Facebook’s own regulations, but also its trustworthiness as an organisation. At the same time, they open the door to misinformation and to advertisers with malicious intentions. Facebook also incorrectly categorises a large number of non-political ads as political. These are the false positives. This also erodes confidence in how effective the platform is at enforcing regulation and has resulted in a situation in which important social information, on topics such as COVID-19, did not reach the public.


The researchers put forward a number of recommendations that may prove useful for the legislative work currently being carried out both in the EU (a.o. Digital Services Act) and in the US. These recommendations aim to ensure that Facebook acts more effectively on its own rules and actually enforces them. Facebook must therefore:

  • closely monitor the pages of parties, candidates and obviously political organisations, and demand that all their ads be declared as political ads;
  • impose consequences for violating the rules, such as taking Facebook pages offline or prohibiting the placing of ads;
  • make sufficient investments in a system that operates globally and takes the local context into account. In order to achieve this, it should engage with local government and local regulators and organisations;
  • clarify what Facebook understand to be a "political" ad.

"Facebook could take some simple measures to improve its detection of political ads, but it has already indicated that it doesn’t feel particularly inclined to do so," says the researcher Victor Le Pochat (KU Leuven). It is also necessary for large advertising platforms to make extensive data on all advertisements widely available, because that is still not happening enough at the moment. "We cannot rely on Facebook to identify and disclose political ads on its own. What is needed is mandatory transparency so that independent research can look for weaknesses in the system and hold the platforms accountable," said Laura Edelson, a co-founder of NYU Cybersecurity for Democracy and co-author of this report.

Emmanuel Rottey, translated by N.N.

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