The article begins with an overview of the major law enforcement electronic surveillance techniques, pen registers, trap, and trace devices and communications interception techniques. Legal access to interception mechanisms is subject to strict regulation and, in the States where it is permitted, is usually limited to use in the investigation of felony offenses and in the event that other less invasive methods would be ineffective or unduly dangerous to law enforcement personnel. The legal framework for the use of electronic surveillance is discussed beginning with the 1967 United States Supreme Court decision in Katz v. United States. Subsequent statutory standards are discussed including the Omnibus Crime Control and Safe Streets Act of 1968, The Electronic Communications and Privacy Act (ECPA) of 1986, and the Communications Assistance for Law Enforcement Act (CALEA). The Federal Bureau of Investigation (FBI) and the Federal Communications Commission (FCC) shared administrative oversight for the CALEA is discussed. CALEA clarifies the scope of common carrier duties regarding electronic surveillance and requires carriers to modify equipment and services as needed to facilitate lawful electronic surveillance and also establishes an affirmative duty for telecommunications equipment manufacturers to develop equipment to support electronic surveillance techniques. That duty and the industry response remains controversial. The initial industry response, interim technical standard J-STD-025 and the United States Telecommunications Association v. the Federal Communications Commission, 227 F.3d 450 (D.C.Cir. 2000) are presented. 3 notes, 1 table