Pen register
Encyclopedia
A pen register is an electronic
device that records all numbers
called from a particular telephone
line. The term has come to include any device or program that performs similar functions to an original pen register, including programs monitoring Internet
communications.
The United States statutes governing pen registers are codified under 18 U.S.C., Chapter 206.
's 1840 telegraph patent described
such a register as consisting of a lever
holding an armature on one end, opposite an electromagnet
, with a fountain pen
, pencil
or other marking instrument on the other end, and a clockwork mechanism to advance a paper recording tape under the marker.
The term telegraph register came to be a generic term for
such a recording device in the later 19th century. See for example, Frank Wood's Telegraph Register. Where the record was made in ink with a pen, the term pen register emerged. By the end of the 19th century, pen registers were widely used to record pulsed electrical signals in many contexts. For example, one fire-alarm system used a "double pen-register",
and another used a "single or multiple pen register".
As pulse dialing
came into use for telephone exchange
s,
pen registers had obvious applications as diagnostic instruments for recording sequences of telephone dial pulses. With the passage of time, any instrument that could be used for this purpose came to be defined as a pen register. Title 18 of the United States Code
defines a pen register as:
This is the current definition of a Pen Register, as amended by passage of the 2001 USA PATRIOT Act
. The original statutory definition of a pen register was created in 1984 as part of the Electronic Communications Privacy Act
, which defined a "Pen Register" as:
A pen register is similar to a trap and trace device
. A trap and trace device would show what numbers had called a specific telephone, i.e. all incoming phone numbers. A pen register rather would show what numbers a phone had called, i.e. all outgoing phone numbers. The two terms are often used in concert, especially in the context of Internet communications. They are often jointly referred to as "Pen Register or Trap and Trace devices," to reflect the fact that the same program will probably do both functions in the modern era, and the distinction is not that important. The term 'pen register' is often used to describe both pen registers and trap and trace devices.
(1967), the United States Supreme Court established its "reasonable expectation of privacy" test. It overturned Olmstead v. United States
and held that wiretap
s were unconstitutional
searches, because there was a reasonable expectation that the communication would be private
. The government was then required to get a warrant
to execute a wiretap.
Ten years later the Supreme Court held that a pen register is not a search because the "petitioner voluntarily conveyed numerical information to the telephone company." Smith v. Maryland
, 442 U.S. 735, 744 (1979). Since the defendant
had disclosed the dialed numbers to the telephone company so they could connect his call, he did not have a reasonable expectation of privacy in the numbers he dialed. The court did not distinguish between disclosing the numbers to a human operator or just the automatic equipment used by the telephone company.
The Smith decision left pen registers completely outside constitutional
protection. If there was to be any privacy protection, it would have to be enacted by Congress as statutory privacy law.
(ECPA) was passed in 1986 (Pub. L. No. 99-508, 100 Stat. 1848). There were three main provisions or Titles to the ECPA. Title III created the Pen Register Act, which included restrictions on private and law enforcement uses of pen registers. Private parties were generally restricted from using them unless they met one of the exceptions, which included an exception for the business providing the communication if it needed to do so to ensure the proper functioning of its business.
For law enforcement agencies
to get a pen register approved for surveillance
, they must get a court order
from a judge. According to 18 U.S.C. § 3123(a)(1), the "court shall enter an ex parte
order authorizing the installation and use of a pen register or trap and trace device anywhere within the United States, if the court finds that the attorney for the Government has certified to the court that the information likely to be obtained by such installation and use is relevant to an ongoing criminal investigation." Thus, a government attorney only needs to certify that information will 'likely' be obtained in relation to an 'ongoing criminal investigation'. This is the lowest requirement for receiving a court order under any of the ECPA's three titles. This is because in Smith v. Maryland
, the Supreme Court ruled that use of a pen register does not constitute a search
. The ruling held that only the content of a conversation should receive full constitutional protection under the right to privacy, since pen registers do not intercept conversation, they do not pose as much threat to this right.
Some have argued that the government should be required to present "specific and articulable facts" showing that the information to be gathered is relevant and material to an ongoing investigation. This is the standard used by Title II of the ECPA with regard to the contents of stored communications. And others believe probable cause
should be required; Daniel Solove, Petricia Bellia, and Dierdre Mulligan say a warrant and probable cause should be necessary, and Paul Ohm argues that standard of proof should be replaced/reworked for electronic communications altogether.
The Pen Register Act did not include an exclusionary rule
. While there were civil remedies for violations of the Act, evidence gained in violation of the Act can still be used against a defendant in court. There have also been calls for congress to add an exclusionary rule
to the Pen Register Act, as this would make it more analogous to traditional Fourth Amendment
protections.
expanded the definition of a pen register to include devices or programs that provide an analogous function with internet communications. Prior to the Patriot Act, it was unclear whether or not the definition of a pen register, which included very specific telephone terminology, could apply to internet communications. Most courts and law enforcement personnel operated under the assumption that it did, however the Clinton administration had begun to work on legislation to make that clear, and one magistrate
judge in California
did rule that the language was too telephone-specific to apply to Internet surveillance.
The Pen Register Statute is a privacy act. As there is no constitutional protection for information divulged to a third party under the Supreme Court's expectation of privacy test, and the routing information for phone and internet communications are divulged to the company providing the communication, the absence or inapplicability of the statute would leave the routing information for those communications completely unprotected from government surveillance.
The government also has an interest in making sure the Pen Register Act exists and applies to internet communications. Without the Act, they cannot compel service providers to give them records or do internet surveillance with their own equipment or software, and the law enforcement agency, which may not have very good technological capabilities, will have to do the surveillance itself at its own cost.
Rather than creating new laws regarding Internet surveillance, the Patriot Act simply expanded the definition of a pen register to include computer software programs doing Internet surveillance. While not completely compatible with the technical definition of a pen register device, this was the interpretation that had been used by almost all courts and law enforcement agencies prior to the change.
, as example of how such domestic spying violated Federal law.
.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
device that records all numbers
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
called from a particular telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
line. The term has come to include any device or program that performs similar functions to an original pen register, including programs monitoring Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
communications.
The United States statutes governing pen registers are codified under 18 U.S.C., Chapter 206.
Definitions
The term pen register originally referred to a device for recording telegraph signals on a strip of paper. Samuel F. B. MorseSamuel F. B. Morse
Samuel Finley Breese Morse was an American contributor to the invention of a single-wire telegraph system based on European telegraphs, co-inventor of the Morse code, and an accomplished painter.-Birth and education:...
's 1840 telegraph patent described
such a register as consisting of a lever
Lever
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...
holding an armature on one end, opposite an electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
, with a fountain pen
Fountain pen
A fountain pen is a nib pen that, unlike its predecessor the dip pen, contains an internal reservoir of water-based liquid ink. The pen draws ink from the reservoir through a feed to the nib and deposits it on paper via a combination of gravity and capillary action...
, pencil
Pencil
A pencil is a writing implement or art medium usually constructed of a narrow, solid pigment core inside a protective casing. The case prevents the core from breaking, and also from marking the user’s hand during use....
or other marking instrument on the other end, and a clockwork mechanism to advance a paper recording tape under the marker.
The term telegraph register came to be a generic term for
such a recording device in the later 19th century. See for example, Frank Wood's Telegraph Register. Where the record was made in ink with a pen, the term pen register emerged. By the end of the 19th century, pen registers were widely used to record pulsed electrical signals in many contexts. For example, one fire-alarm system used a "double pen-register",
and another used a "single or multiple pen register".
As pulse dialing
Pulse dialing
Pulse dialing, dial pulse, or loop disconnect dialing, also called rotary or decadic dialling in the United Kingdom , is pulsing in which a direct-current pulse train is produced by interrupting a steady signal according to a fixed or formatted code for each digit and at a standard pulse repetition...
came into use for telephone exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
s,
pen registers had obvious applications as diagnostic instruments for recording sequences of telephone dial pulses. With the passage of time, any instrument that could be used for this purpose came to be defined as a pen register. Title 18 of the United States Code
United States Code
The Code of Laws of the United States of America is a compilation and codification of the general and permanent federal laws of the United States...
defines a pen register as:
- a device or process which records or decodes routing, addressing, or signalling information transmitted by an instrument or facility from which a wire or electronic communication is transmitted, provided, however, that such information shall not include the contents of any communication, but such term does not include any device or process used by a provider or customer of a wire or electronic communication service for billing, or recording as an incident to billing, for communications services provided by such provider or any device or process used by a provider or customer of a wire communication service for cost accounting or other like purposes in the ordinary course of its business.
This is the current definition of a Pen Register, as amended by passage of the 2001 USA PATRIOT Act
USA PATRIOT Act
The USA PATRIOT Act is an Act of the U.S. Congress that was signed into law by President George W. Bush on October 26, 2001...
. The original statutory definition of a pen register was created in 1984 as part of the Electronic Communications Privacy Act
Electronic Communications Privacy Act
The Electronic Communications Privacy Act is a United States law.- Overview :The “electronic communication” means any transfer of signs, signals, writing, images, sounds, data, or intelligence of any nature transmitted in whole or in part by a wire, radio, electromagnetic, photoelectronic or...
, which defined a "Pen Register" as:
- A device which records or decodes electronic or other impulses which identify the numbers called or otherwise transmitted on the telephone line to which such device is dedicated.
A pen register is similar to a trap and trace device
Trap and trace device
A trap and trace device is an electronic device used to record and trace all communication signals from a telecommunication system. An analogous feature available for use by the general public would be Caller ID....
. A trap and trace device would show what numbers had called a specific telephone, i.e. all incoming phone numbers. A pen register rather would show what numbers a phone had called, i.e. all outgoing phone numbers. The two terms are often used in concert, especially in the context of Internet communications. They are often jointly referred to as "Pen Register or Trap and Trace devices," to reflect the fact that the same program will probably do both functions in the modern era, and the distinction is not that important. The term 'pen register' is often used to describe both pen registers and trap and trace devices.
Background
In Katz v. United StatesKatz v. United States
Katz v. United States, , is a United States Supreme Court case discussing the nature of the "right to privacy" and the legal definition of a "search." The Court’s ruling adjusted previous interpretations of the unreasonable search and seizure clause of the Fourth Amendment to count immaterial...
(1967), the United States Supreme Court established its "reasonable expectation of privacy" test. It overturned Olmstead v. United States
Olmstead v. United States
Olmstead v. United States, , was a decision of the Supreme Court of the United States, in which the Court reviewed whether the use of wiretapped private telephone conversations, obtained by federal agents without judicial approval and subsequently used as evidence, constituted a violation of the...
and held that wiretap
Telephone tapping
Telephone tapping is the monitoring of telephone and Internet conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitoring connection was an actual electrical tap on the telephone line...
s were unconstitutional
Constitutionality
Constitutionality is the condition of acting in accordance with an applicable constitution. Acts that are not in accordance with the rules laid down in the constitution are deemed to be ultra vires.-See also:*ultra vires*Company law*Constitutional law...
searches, because there was a reasonable expectation that the communication would be private
Privacy
Privacy is the ability of an individual or group to seclude themselves or information about themselves and thereby reveal themselves selectively...
. The government was then required to get a warrant
Warrant (law)
Most often, the term warrant refers to a specific type of authorization; a writ issued by a competent officer, usually a judge or magistrate, which permits an otherwise illegal act that would violate individual rights and affords the person executing the writ protection from damages if the act is...
to execute a wiretap.
Ten years later the Supreme Court held that a pen register is not a search because the "petitioner voluntarily conveyed numerical information to the telephone company." Smith v. Maryland
Smith v. Maryland
Smith v. Maryland, 442 U.S. 735 , was a case in which the Supreme Court of the United States held that the installation and use of the pen register was not a "search" within the meaning of the Fourth Amendment, and hence no warrant was required....
, 442 U.S. 735, 744 (1979). Since the defendant
Defendant
A defendant or defender is any party who is required to answer the complaint of a plaintiff or pursuer in a civil lawsuit before a court, or any party who has been formally charged or accused of violating a criminal statute...
had disclosed the dialed numbers to the telephone company so they could connect his call, he did not have a reasonable expectation of privacy in the numbers he dialed. The court did not distinguish between disclosing the numbers to a human operator or just the automatic equipment used by the telephone company.
The Smith decision left pen registers completely outside constitutional
United States Constitution
The Constitution of the United States is the supreme law of the United States of America. It is the framework for the organization of the United States government and for the relationship of the federal government with the states, citizens, and all people within the United States.The first three...
protection. If there was to be any privacy protection, it would have to be enacted by Congress as statutory privacy law.
Pen Register Act
The Electronic Communications Privacy ActElectronic Communications Privacy Act
The Electronic Communications Privacy Act is a United States law.- Overview :The “electronic communication” means any transfer of signs, signals, writing, images, sounds, data, or intelligence of any nature transmitted in whole or in part by a wire, radio, electromagnetic, photoelectronic or...
(ECPA) was passed in 1986 (Pub. L. No. 99-508, 100 Stat. 1848). There were three main provisions or Titles to the ECPA. Title III created the Pen Register Act, which included restrictions on private and law enforcement uses of pen registers. Private parties were generally restricted from using them unless they met one of the exceptions, which included an exception for the business providing the communication if it needed to do so to ensure the proper functioning of its business.
For law enforcement agencies
Law enforcement agency
In North American English, a law enforcement agency is a government agency responsible for the enforcement of the laws.Outside North America, such organizations are called police services. In North America, some of these services are called police while others have other names In North American...
to get a pen register approved for surveillance
Surveillance
Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...
, they must get a court order
Court order
A court order is an official proclamation by a judge that defines the legal relationships between the parties to a hearing, a trial, an appeal or other court proceedings. Such ruling requires or authorizes the carrying out of certain steps by one or more parties to a case...
from a judge. According to 18 U.S.C. § 3123(a)(1), the "court shall enter an ex parte
Ex parte
Ex parte is a Latin legal term meaning "from one party" .An ex parte decision is one decided by a judge without requiring all of the parties to the controversy to be present. In Australian, Canadian, U.K., Indian and U.S...
order authorizing the installation and use of a pen register or trap and trace device anywhere within the United States, if the court finds that the attorney for the Government has certified to the court that the information likely to be obtained by such installation and use is relevant to an ongoing criminal investigation." Thus, a government attorney only needs to certify that information will 'likely' be obtained in relation to an 'ongoing criminal investigation'. This is the lowest requirement for receiving a court order under any of the ECPA's three titles. This is because in Smith v. Maryland
Smith v. Maryland
Smith v. Maryland, 442 U.S. 735 , was a case in which the Supreme Court of the United States held that the installation and use of the pen register was not a "search" within the meaning of the Fourth Amendment, and hence no warrant was required....
, the Supreme Court ruled that use of a pen register does not constitute a search
Search and seizure
Search and seizure is a legal procedure used in many civil law and common law legal systems whereby police or other authorities and their agents, who suspect that a crime has been committed, do a search of a person's property and confiscate any relevant evidence to the crime.Some countries have...
. The ruling held that only the content of a conversation should receive full constitutional protection under the right to privacy, since pen registers do not intercept conversation, they do not pose as much threat to this right.
Some have argued that the government should be required to present "specific and articulable facts" showing that the information to be gathered is relevant and material to an ongoing investigation. This is the standard used by Title II of the ECPA with regard to the contents of stored communications. And others believe probable cause
Probable cause
In United States criminal law, probable cause is the standard by which an officer or agent of the law has the grounds to make an arrest, to conduct a personal or property search, or to obtain a warrant for arrest, etc. when criminal charges are being considered. It is also used to refer to the...
should be required; Daniel Solove, Petricia Bellia, and Dierdre Mulligan say a warrant and probable cause should be necessary, and Paul Ohm argues that standard of proof should be replaced/reworked for electronic communications altogether.
The Pen Register Act did not include an exclusionary rule
Exclusionary rule
The exclusionary rule is a legal principle in the United States, under constitutional law, which holds that evidence collected or analyzed in violation of the defendant's constitutional rights is sometimes inadmissible for a criminal prosecution in a court of law...
. While there were civil remedies for violations of the Act, evidence gained in violation of the Act can still be used against a defendant in court. There have also been calls for congress to add an exclusionary rule
Exclusionary rule
The exclusionary rule is a legal principle in the United States, under constitutional law, which holds that evidence collected or analyzed in violation of the defendant's constitutional rights is sometimes inadmissible for a criminal prosecution in a court of law...
to the Pen Register Act, as this would make it more analogous to traditional Fourth Amendment
Fourth Amendment to the United States Constitution
The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause...
protections.
USA-PATRIOT Act
Section 216 of the 2001 USA PATRIOT ActUSA PATRIOT Act
The USA PATRIOT Act is an Act of the U.S. Congress that was signed into law by President George W. Bush on October 26, 2001...
expanded the definition of a pen register to include devices or programs that provide an analogous function with internet communications. Prior to the Patriot Act, it was unclear whether or not the definition of a pen register, which included very specific telephone terminology, could apply to internet communications. Most courts and law enforcement personnel operated under the assumption that it did, however the Clinton administration had begun to work on legislation to make that clear, and one magistrate
Magistrate
A magistrate is an officer of the state; in modern usage the term usually refers to a judge or prosecutor. This was not always the case; in ancient Rome, a magistratus was one of the highest government officers and possessed both judicial and executive powers. Today, in common law systems, a...
judge in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
did rule that the language was too telephone-specific to apply to Internet surveillance.
The Pen Register Statute is a privacy act. As there is no constitutional protection for information divulged to a third party under the Supreme Court's expectation of privacy test, and the routing information for phone and internet communications are divulged to the company providing the communication, the absence or inapplicability of the statute would leave the routing information for those communications completely unprotected from government surveillance.
The government also has an interest in making sure the Pen Register Act exists and applies to internet communications. Without the Act, they cannot compel service providers to give them records or do internet surveillance with their own equipment or software, and the law enforcement agency, which may not have very good technological capabilities, will have to do the surveillance itself at its own cost.
Rather than creating new laws regarding Internet surveillance, the Patriot Act simply expanded the definition of a pen register to include computer software programs doing Internet surveillance. While not completely compatible with the technical definition of a pen register device, this was the interpretation that had been used by almost all courts and law enforcement agencies prior to the change.
NSA call database controversy
When, in 2006, the Bush administration came under fire for having secretly collected billions of phone call details from regular Americans, ostensibly to check for calls to terror suspects, the Pen Register Act was cited, along with the Stored Communications ActStored Communications Act
The Stored Communications Act is a law that was enacted by the United States Congress in 1986. It is not a stand-alone law but forms part of the Electronic Communications Privacy Act; it is codified as 18 U.S.C. §§ 2701 to 2712...
, as example of how such domestic spying violated Federal law.
Pen registers in popular culture
Pen registers are frequently referred to in the HBO crime drama, The WireThe WIRE
the WIRE is the student-run College radio station at the University of Oklahoma, broadcasting in a freeform format. The WIRE serves the University of Oklahoma and surrounding communities, and is staffed by student DJs. The WIRE broadcasts at 1710 kHz AM in Norman, Oklahoma...
.