Federal law prohibits the interception of electronic communications of another person under the Electronic Communications Privacy Act of 1986, states the U.S. Department of Justice. The term "electronic communication" includes text messages between mobile phones. Although this is the general rule under federal law, there are exceptions.
The Electronic Communications Privacy Act, codified as 18 U.S.C. § 2510-22, is federal law applicable to all United States jurisdictions. Title I of the Act prohibits anyone from intentionally intercepting another person's electronic communications and forbids the use or disclosure of that information. The ECPA also prohibits the procurement of another person to intercept text messages on someone's behalf. Even the attempt of intercepting an individual's text messages is prohibited under this Act and carries a penalty under federal law, notes the U.S. Department of Justice.
In some cases, individuals and entities authorized under other federal laws can intercept text messages without violating the ECPA. For example, the Foreign Intelligence Surveillance Act allows for certain individuals to intercept electronic communications for purposes of obtaining foreign intelligence, explains the Legal Information Institute of Cornell University Law School.