News from the ad archive: how journalists use the Facebook Ad Library to hold online advertising accountable

The Facebook Ad Library promises to improve transparency and accountability in online advertising by rendering personalised campaigns visible to the public. This article investigates whether and how journalists have made use of this tool in their reporting. Our content analysis of print journalism reveals several different use cases, from high-level reporting on political campaigns to uncovering specific wrongdoings such as disinformation, hate speech, and astroturfing. However, our interviews with journalists who use the Ad Library show that they remain highly critical of this tool and its manifold limitations. We argue that these findings offer empirical grounding for the public regulation of ad archives, since they underscore both the public interest in advertising disclosures as well as the growing reliance of journalists on voluntary and incomplete access frameworks controlled by the very platforms they aim to scrutinise.