Codes of the Underworld: How Criminals Communicate Book

This is a quick and accessible survey of the various ways in which criminals use signalling to communicate. The central insight here is that criminals (like everyone, but exacerbated by the illicit nature of their profession) face significant challenges in developing trust and verifying credibility during exchanges, which forces a variety of signalling responses depending on the type of interaction. This can range from facial tattoos to forms of initiation that require prospective partners to engage in joint criminal acts to prove their loyalty and strengthen group solidarity. Two chapters study how prisoners engage in fighting or self-harm in order to signal their toughness relative to their peers. Other chapters look at brand names in the drug trade, the use of nicknames by mafia members as a means of obscuring identities, and how media portrayals of criminal groups affect their self-identities.

There is no strong analytical narrative tying all the chapters of the book together, and the analysis primarily takes place at the individual level. Jacob Shapiro's The Terrorist's Dilemma is better for exploring how the need to operate in secret imposes constraints on clandestine organizations' activities. Still, this was an easy and interesting read.