Privacy Law is a relatively nascent and murky interdisciplinary field of law. Considered in light of a ballooning and developing world of contextual tech (mobile, social media, Big Data and "little data," sensors, geo-location services, etc.), this field of law and the legal and policy decisions made in connection to it, to me, are glimpses of a future (perhaps dystopian to some) in which privacy considerations will, in terms of substantive law, categorically reign above most else. Even more interestingly, other areas of law are necessarily implicated. Comparative Law, for instance, is subsumed under considerations surrounding privacy. To illustrate, the US and EU regulatory regimes differ greatly with respect to how each conceptually views privacy--this can be attributed in part to cultural and anthropological differences between the two. EU Law (e.g., German Basic Law) places great value in citizens' Right to Personality and Right to be Forgotten, to name a few, whereas the US embraces an "everything is fair game"/safe harbor mentality that is markedly less rigorous in regulatory terms. And we've seen what such a lack of uniformity produces: several US-based multinational companies inevitably butting heads with EU regulators (e.g., Google, Facebook, etc.).
Here is a great overview on the different types of Privacy Law that I recently came across. The attachment is sourced from a larger work, Privacy Law Fundamentals by Daniel J. Solove and Paul M. Schwartz.