Legal Definitions - National Security Letter

A National Security Letter is a type of order that the government can use to force people or organizations to give them information. These letters were created by the USA PATRIOT Act, which was a law passed after the 9/11 terrorist attacks.

When the government sends a National Security Letter, they can also include a gag order. This means that the person or organization who receives the letter is not allowed to talk about it with anyone else. The letters do not need to be approved by a judge, and there is only limited review by the courts.

The Federal Bureau of Investigation (FBI) has used National Security Letters in the past. However, in a court case called Doe v. Mukasey, a court decided that the gag orders and lack of judicial review violated the First Amendment of the United States Constitution.

For example, if the government thinks that a person is involved in terrorism, they might send a National Security Letter to that person's internet service provider (ISP). The letter would order the ISP to give the government information about the person's internet activity. The gag order would prevent the ISP from telling the person that the government had asked for their information.