The Electronic Communications Privacy Act of 1986 (ECPA) is a federal law that regulates the privacy of wire, oral, and electronic communications. The ECPA prohibits the intentional interception, use, or disclosure of such communications, unless authorized by law or by the consent of one of the parties to the communication12. The ECPA also provides exceptions for certain types of communications, such as those made in the normal course of business, those made for law enforcement purposes, or those made for foreign intelligence purposes12.
One of the exceptions to the ECPA ban on interception is where one of the parties has given consent. This means that if a person who is a party to a communication agrees to have it intercepted, the interception is lawful under the ECPA. Consent can be express or implied, depending on the circumstances and the expectations of the parties3. For example, if a person calls a customer service line and hears a recorded message that the call may be monitored or recorded, the person has impliedly consented to the interception of the call. However, if a person calls a friend and does not know that the friend has a third party listening in on the call, the person has not consented to the interception of the call.
References: 1: Electronic Communications Privacy Act of 1986, 18 U.S.C. §§ 2510-2523 2: [IAPP CIPP/US Study Guide], Chapter 8, Section 8.2.1. 3: [Searching and Seizing Computers and Obtaining Electronic Evidence in Criminal Investigations], pp. 77-78.