Measuring the Emergence of Consent Management on the Web

Abstract

Privacy laws like the General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA) have pushed internet firms processing personal data to obtain user consent. Uncertainty around sanctions for non-compliance led many websites to embed a Consent Management Provider (CMP), which collects users' consent and shares it with third-party vendors and other websites. Our paper maps the formation of this ecosystem using longitudinal measurements. Primary and secondary data sources are used to measure each actor within the ecosystem. Using 161 million browser crawls, we estimate that CMP adoption doubled from June 2018 to June 2019 and then doubled again until June 2020. Sampling 4.2 million unique domains, we observe that CMP adoption is most prevalent among moderately popular websites (Tranco top 50-10k) but a long tail exists. Using APIs from the ad-tech industry, we quantify the purposes and lawful bases used to justify processing personal data. A controlled experiment on a public website provides novel insights into how the time-to-complete of two leading CMPs' consent dialogues varies with the preferences expressed, showing how privacy aware users incur a significant time cost.