|Bruce Hubbard's email to the United States embassy accused the superpower of dropping napalm on babies, invading 72 countries and having Nazi leanings.
On Monday, the 38-year-old Auckland peace activist will appear in the North Shore District Court charged with misusing a telephone - for which he could receive up to three months in jail or a $2000 fine.
The police reaction to Hubbard's email has civil libertarians worried about free expression and the new Counter-Terrorism Act, which they say could be used to curb peaceful protest.
Hubbard and fellow activist John Minto say police have threatened to seize Hubbard's computer under the act and delve into his files on peace activities.
But police say a woman at the embassy was offended by the email and they have no intention of seizing Hubbard's computer.