The book: The Knockoff Economy: How Imitation Sparks Innovation, by Kal Raustiala and Christopher Sprigman; Oxford University Press

The big idea: Patents, copyrights, and their defensive brethren are intended to motivate creative types. But in industries ranging from fashion to financial services, freedom to copy fuels innovation.

The backstory: Raustiala and Sprigman are law professors at UCLA and the University of Virginia, respectively.

Peer police: Social norms can be more effective than regulation, say the authors. Standup comics adhere to a set of informal but widely accepted gag laws (for example, being the first to deliver a joke on TV is like getting a patent on it). Famous chefs are cool with others copying their recipes--so long as they give credit and don't copy them exactly. Performing another magician's trick is OK. But reveal the secret to that trick, and you may get sawed in half.

If you read nothing else: The last chapter revisits main themes, such as how copying creates demand by speeding up the fashion cycle and serving as an advertisement for brands. But the book is fun, and if you skip the rest, you'll never know how the advent of the player piano led to lenient laws on cover songs or about the firm that tried to patent the peanut butter and jelly sandwich.

Rigor rating:  8 (1=Who Moved My Cheese?; 10=Good to Great)
The authors' broad knowledge of case law is evident in the lengthy notes section.