A system and method that evaluates privacy policies from web sites to determine whether each site is permitted to perform operations (e.g., store, retrieve or delete) directed to cookies on a user's computer. Various properties of each cookie and the context in which it is being used are evaluated against a user's privacy preference settings to make the determination. An evaluation engine accomplishes the evaluation and determination via a number of criteria and considerations, including the cookie properties, its current context, the site, the zone that contains the site, and any P3P data (compact policy) provided with the site's response. The user privacy preferences are evaluated against these criteria to determine whether a requested cookie operation is allowed, denied or modified. A formalized distinction between first-party cookies versus third-party cookies may be used in the determination, along with whether the cookie is a persistent cookie or a session cookie.