Ann Cavoukian, A Primer on Metadata: Separating Fact from Fiction (July 2013) (full-text).
This paper, written by the Information & Privacy Commissioner, Ontario, Canada, explains that metadata can actually be more revealing than accessing the content of our communications. The paper aims to provide a clear understanding of metadata and disputes popular claims that the information being captured is neither sensitive, nor privacy-invasive, since it does not access any content. Given the implications for privacy and freedom, it is critical that we all question the dated, but ever-so prevalent either/or, zero-sum mindset to privacy vs. security. Instead, what is needed are proactive measures designed to provide for both security and privacy, in an accountable and transparent manner.