This book delves into the core debates of criminal law, examining fundamental principles such as legality, protection of legally protected goods, culpability, and proportionality. It reinterprets these principles through a lens of a Rawlsian theory of justice, proposing them as deontological liberalistic principles of justice. The book explores the influence of enlightenment thought and social contract theory which have sophisticatedly evolved so far on criminal law, suggesting that these principles can be derived from a hypothetical agreement under fair participation conditions. Covering a wide range of topics, the book addresses human dignity, culpability, and the prohibition of analogy in criminal law interpretation. It engages with classic and ongoing debates, including free will, legal indeterminacy, and the jurisprudential implication of philosophies of Wittgenstein and Gödel. Additionally, it critically examines some theoretical issues, including collective guilt, criminal liability of electronic person, psychopathic offender, and conscientious objectors, as well as such doctrinal issues as mistaken self-defence and criminal complicity. A chapter on the origins of the penal system provides an in-depth account based on ancient Near Eastern customs and the Hammurabi Code, enriched by the latest evolutionary research. This interdisciplinary approach offers a comprehensive understanding of the nature of punishment.