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.Although this was generally sufficient for law-enforcement use in the past, law-enforcement agencieshave recently begun pushing for vastly expanded wiretapping facilities. Pen Register and Trap and TraceAs we noted in the previous chapter, the backbone of a communications intelligence organization isnot its ability to read individual messages, valuable as that is, but its ability to keep track of a broadspectrum of communications through traffic analysis.Although this is less true of law enforcementintercepts, a sort of traffic analysis, generally targeted at individual lines, plays an important rolehere.A log of the numbers of all phones called by one particular phone is called a pen register.11 In theUnited States the ability to record called numbers has been an essential component of billing for along time and thus has been built into telephone equipment for a long time.12 Call logging can alsobe carried out by equipment on a subscriber's premises (Jupp 1989).The inverse activity taking note of the numbers of all phones that call a particular phone is calledtrap and trace.Unlike logging the numbers of outgoing calls, this was very difficult before thechanges made during the past two decades in telephone signaling.13 In the era of electro-mechanicaltelephone switching, call tracing took many minutes, during which the caller had to be kept on theline.14 With digital switching, however, tracing information is almost always available until at leastthe last switch through which the call passes, and it is often available to the receiving telephone in theform of Caller ID.15As in intelligence work, analysis of the patterns of telephone calls can reveal the structures oforganizations and the movements of people.Where billing records preserve such information, it canbe employed after the fact, even though the need to do so was not anticipated.16Electronic Surveillance in ContextTo be understood correctly, electronic surveillance must be seen in the context of the use oftechnology by police.Police have often been at the forefront of the use of new technologies.Scotland Yard was connectedto the district police stations of London by telegraph in 1849, only 5 years after the telegraph wasinvented.In 1878 the Chicago police introduced telephone boxes along policemen's routes.''Wirephoto," credited with the capture of a criminal as early as 1908, became widespread after WorldWar I. Some elements of today's police technology are entirely new; others have clearly recognizable rootsbut have changed so much that they are only barely recognizable in relation to their ancestral forms.The most basic of these are the technologies that shape the operations of a police organization: recordkeeping and what we will call by the military term "command and control."Police records serve both a strategic and a tactical function.Strategically, they allow police to decidehow to deploy their forces.Tactically, they provide information on persons, property, and eventsconnected with the investigation of individual crimes.Police records were once local to cities ordistricts, and sharing of information between police was a slow, uncertain process.Today, however, acomputerized National Crime Information Center provides information to federal, state, and localpolice forces throughout the United States.This source of information is augmented by police accessto commercial credit databases, national telephone directories, and other online information services.The utility of records is closely connected to another mainstay of police technology:communications.Today most on-duty officers, whether patrolling in cars or walking beats, are inimmediate radio contact with their stations.Police cars in some cities carry data terminals that allowdirect access to printed records; in other places, officers on patrol must make voice contact with adispatcher who has access to databases.Police forces today not only have access to nationwide (andoften worldwide) records, but much of that access is directly available to officers in the field.Radio communication also gives the dispatcher immediate access to officers on patrol.To utilize thiseffectively, the dispatcher must have information about where the officers are and what they aredoing
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