Evaluating Privacy Policies under Modern Privacy Laws At Scale: An LLM-Based Automated Approach

Website privacy policies detail an online service's information practices, including how they handle user data and rights. For many sites, these disclosures are now necessitated by a growing set of privacy regulations, such as GDPR and multiple US state laws, offering visibility into privacy practices that are often not publicly observable. Motivated by this visibility, prior work has explored techniques for automated analysis of privacy policies and characterized specific aspects of realworld policies on a larger scale. However, existing approaches are constrained in the privacy practices they evaluate, as they rely upon rule-based methods or supervised classifiers, and many predate the prominent privacy laws now enacted that drastically shape privacy disclosures. Thus, we lack a comprehensive understanding of modern website privacy practices disclosed through privacy policies. In this work, we seek to close this gap by providing a systematic and comprehensive evaluation of website privacy policies at scale. We first systematize the privacy practices discussed by 10 notable privacy regulations currently in effect in the European Union and the US, identifying 34 distinct clauses on privacy practices across 4 overarching themes. We then develop and evaluate an LLM-based approach for assessing these clauses in privacy policies, providing a more accurate, comprehensive, and flexible analysis compared to prior techniques. Finally, we collect privacy policies from over 100K websites, and apply our LLM method to a subset of sites to investigate in-depth the privacy practices of websites today. Ultimately, our work supports broader investigations into web privacy practices moving forward.