At that time, Zimmermann feared the US would outlaw domestic use of strong encryption software, so he worked hard to bring out PGP while encryption was still legal. Released on the Internet free of charge, PGP quickly achieved worldwide popularity.
Violation is a felony.
In September 1993, two years after PGP's release, US customs agents served subpoenas to Viacrypt in Phoenix, Arizona, and Austin Code Works in Austin, Texas. Viacrypt is working closely with Zimmermann on a version of PGP for commercial use. Neither Zimmermann nor the two companies have been charged with any crimes as we go to press. All announced their resolve to defend consumer choice in encryption products. Zimmermann's attorney, Philip Dubois, points out that charging Zimmermann would also raise fundamental civil rights issues.