Individual concern over privacy has existed as long as humans have said or done things they do not wish others to know about. In their groundbreaking law review article The Right to Privacy, Warren and Brandeis posited that the common law should protect an individual's right to privacy under a right formulated as the right to be let alone-Privacy 1.0. As technology advanced and societal values also changed, a belief surfaced that the Warren and Brandeis formulation did not provide sufficient structure for the development of privacy laws. As such, a second theoretical construct of privacy, Privacy 2.0 as expressed in Dean Prosser's work Privacy was created. Dean Prosser continued (or expanded) upon the concepts formulated by Warren and Brandeis, particularly in emphasizing the role of common law in protecting privacy. These works, while influential in their time, do not account for paradigm shifts in technology, or, perhaps more importantly, changes in how people live their lives. The unending advance of technology and changes in societal norms fundamentally dictate that privacy theory must change over time, or it will lose its relevance. Indeed, in today ' Web 2.0 world where many people instantly share very private aspects of their lives, one can hardly imagine a privacy concept more foreign than the right to be let alone. The question confronting modern-day privacy scholars is this: Can a common law based theory adequately address the shifting societal norms and rapid technological changes of today's Web 2.0 world where legislatures and government agencies, not courts, are more proactive on privacy protections? This Article argues that the answer is no and instead argues that the overarching principle of privacy of today should not be the right to be let alone, but rather the principle of proportionality. This is Privacy 3. 0.