Final answer:
The Electronic Communications Privacy Act (ECPA) is the law that protects email messages from unauthorized interception, requiring law enforcement to obtain a warrant for access.
Step-by-step explanation:
The law that protects e-mail messages from unauthorized interception is the Electronic Communications Privacy Act (ECPA). Enacted in 1986, ECPA addresses issues related to the privacy of electronic communications, including the unauthorized interception and access of electronic communications by government agencies and other entities.
While the Fourth Amendment provides a broader protection against unreasonable searches and seizures, ECPA specifically extends these protections to electronic communications, requiring law enforcement to obtain a warrant to access private email messages. It is worth noting that subsequent amendments and legal acts, such as the USA PATRIOT Act and related court decisions like Carpenter v. United States, have impacted the scope and enforcement of ECPA.