Tim Harford, Slate's "Undercover Economist," explores the secret behind how magicians protect their secrets, drawing from the research of Yale law student Jacob Loshin.

The modern laws that safeguard most intellectual property offer poor protection for magic tricks. Instead, magicians rely on social pressure:

Lacking legal protection, they resort to professional norms.

Loshin describes the magicians' norms, which encourage the selective sharing of techniques, limit copying unless a technique has been widely distributed, and credit the rediscoverer of a long-dormant technique with the same rights as the trick's inventor. Economists Emmanuelle Fauchart and Eric von Hippel report very similar norms for the sharing of recipes among French chefs. ...

These techniques work because the fraternity of magicians--and chefs--is close-knit. Aspiring chefs work long apprenticeships and rely on word-of-mouth for their next job. Magic journals are not available at newsstands, and even Prince Charles had to perform an examination before being accepted as a member of the Magic Circle. A magician who steals from another, or reveals secrets not widely known by nonmagicians, will not be entrusted with new ideas or recommended by other magicians.