Lavabit Founder Waged Privacy Fight as FBI Pursued Snowden

One day last May, Ladar Levison returned home to find an Federal Bureau of Investigation agent’s business card on his Dallas doorstep. So began a four-month tangle with law enforcement officials that would end with Levison’s shutting the business he had spent a decade building and becoming an unlikely hero of privacy advocates in their escalating battle with the government over Internet security.

Prosecutors, it turned out, were pursuing a notable user of Lavabit, Levison’s secure e-mail service: Edward J. Snowden, the former National Security Agency contractor who leaked classified documents that have put the intelligence agency under sharp scrutiny. Levison was willing to allow investigators with a court order to tap Mr. Snowden’s e-mail account; he had complied with similar narrowly targeted requests involving other customers about two dozen times. But they wanted more, he said: the passwords, encryption keys and computer code that would essentially allow the government untrammeled access to the protected messages of all his customers. That, he said, was too much.