When states keep secrets, who decides which ones are worth keeping?

And why does it matter if Edward Snowden is a hero or a narcissist?

Secrets and Leaks:
the Dilemmas of State Secrecy
Rahul Sagar
Princeton, 304pp, £27.95

When states keep secrets, who decides which ones are worth keeping? This is one of the questions that underpinned the recent parliamentary debate about oversight of the security services, following Edward Snowden’s NSA revelations. The conventional answer is that the executive decides – which in the US means the presidency.