Monday, March 4, 2013

Should United States v. Jones Affect Law Enforcement’s Use of Automatic License Plate Recognition Readers?

In United States v. Jones,[1] the United States Supreme Court held that the physical attachment of a Global Positioning System[2] (GPS) tracking device on a vehicle constituted a search under the Fourth Amendment[3]of the United States Constitution.  This decision has left law enforcement questioning the policies and procedures they can employ when utilizing technology to track and store information on individuals suspected of criminal conduct.  The reality is that technology is constantly changing.  Law enforcement needs to be able to change and adapt to the technology in order to use the technology to enhance the investigation of criminal activity.

The Automatic License Plate Recognition reader, more commonly referred to as an ALPR, has quickly become a common tool utilized by law enforcement throughout many police departments.[4]  The ALPR uses digital cameras mounted on a law enforcement vehicle or at stationary locations to snap images of passing license plates.[5]  As a vehicle approaches, the ALPR takes a series of photographs and stores them in a digital file.  The most advanced can photograph up to 1,800 license plates per minute at a speed of up to 140 miles per hour.  These digital photographs are transmitted to a computer system inside of the vehicle and optical character recognition software converts the plate numbers in the photographs into text.  Once converted, the ALPR system compares the plate numbers to available databases, often called hotlists, including lists of stolen automobiles, active arrest warrants, suspended licenses and registrations, and AMBER alerts.  This is a valuable tool for law enforcement as it essentially observes and compares information faster than an officer would be able to do and then notifies the officer when a license plate matches something on a hotlist.
Some departments are using the ALPR not just for this observational comparison, but also for data collection.  Meaning they not only alert an officer as to whether a license plate has hit on a hotlist, but it also tracks the time and date of every license plate it reads.  This information is placed in a searchable database whether or not any evidence of wrong doing was found and the information can be stored indefinitely. [6]
It is not difficult for law enforcement to easily determine the likely driver of a given car by cross-referencing a license plate number with state motor vehicle records.  With enough ALPR systems installed in a community, law enforcement could theoretically create an accurate and pervasive record of a person’s movements over months or years.  This of course can be very helpful for law enforcement in cases of child abduction for example.  Essentially, after the report of a child abduction, law enforcement can pull all registered license plate owners in the area of the abduction at the time it occurred.     

The American Civil Liberties Union (ACLU) however, has expressed concerns about police departments that are gathering and storing information about the travel patterns of all vehicles, regardless of whether they are vehicles of interest.[7]  The fear from a privacy standpoint is that once it is effectively deployed nationwide, it can be used as a kind of mass, warrantless tracking system.[8] Such concerns prompted state Rep. Todd Rutherford, D-Columbia to propose a bill in the South Carolina House that would ban the technology in the state.[9] “There is nothing to protect [the data],” Rutherford  said “All they are doing is collecting it.”[10] According to the ACLU, there are currently only two states, Maine and New Hampshire, with “positive laws” governing how the technology can be used.  New Hampshire bans them, and Maine requires data to be deleted after twenty-one days unless it is part of an investigation.[11] The ACLU says “responsible deletion of data is the exception, not the norm.” [12]
In light of the Jones decision, the ALPR will not likely mandate any type of judicial review.  The ALPR is not a device that is placed on any individual’s vehicle for the purposes of tracking the person.  The ALPR is installed on law enforcements’ vehicles and it indiscriminately reads license plates and compares them to databases which contain hotlists of wanted suspects and traffic offenses listed to their registration or license.  The Court determined in Jones, that a search now occurs both when there is a state-law trespass on property and when the government infringes upon a reasonable expectation of privacy.[13]  The Court explained that “Katz did not narrow the Fourth Amendment’s scope.”[14]  The Court further opined Katz, “established that ‘property rights are not the sole measure of Fourth Amendment violations,’ but did not ‘snuf[f] out the previously recognized protection for property.”[15]
Additionally the Court has set precedent that people have no reasonable expectation of privacy in public spaces, because “the police cannot reasonably be expected to avert their eyes from evidence of criminal activity that could have been observed by any member of the public.”[16]  Further, in Knotts, the Court concluded that “a person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.”[17]  Finally, the ALPR does not give police any extrasensory ability or intrude in the home as the Court found to be the troubling factor in Kyllo.[18]

The data compilation kept by law enforcement likely will not be considered a Fourth Amendment violation either.  The Court in Smith v. Maryland[19], held that warrantless access to pen registers raises no Fourth Amendment concerns.  The court reasoned that a person ought to understand that her phone company may collect a record of all the phone numbers she dials.  The Court further rationalized that a person voluntarily turns over this information to the phone company and should reasonably expect this information to be possibly conveyed to others.  Thus a person traveling in a community that utilizes ALPR should reasonably expect that their license plates may be read by advanced technologies and recorded into a database.  The truth is that most ALPR’s are not only utilized by law enforcement but  are used also as a method of electronic toll collection on pay-per-use roads and cataloging the movements of traffic or individuals like E-ZPass.[20]  Law enforcement can easily subpoena information on registration plates captured by these entities as well.   Justice Sotomayor, in Jones, did caution in her concurring opinion that this third party issue may need to be accessed again when pertaining to information given over by an individual to third parties, however until it is, law enforcement should be safe to track suspects of criminal activity through the use of an ALPR reader.

Diana Cobo
Junior Blog Editor,  Criminal Law Brief

Image by: Whirling Phoenix

[1] See United States v. Jones, 132 S. Ct. 945 (2012).  Available at,21&as_vis=1
[2] U.S. Air Force Fact Sheet: Global Positioning Systems Directorate, L.A. Air Force Base (Jan. 7, 2011),  available at
[3] U.S. Const. amend. IV.
[5] Stephen Rushin, The Judicial Response To Mass Police Surveillance, 2011 U. Ill. J.L. Tech. and Pol’y 281, 285 (2011).
[6] ACLU, Automatic License Plate Readers:  Are You Being Followed? Available at
[7] Rebecca DiLeonardo, ACLU requests information on automatic license plate readers, Jurist; available at
[8]Ryan Gallagher, Police Across U.S. Quietly Turning to Cameras That Track All Vehicles’ Movements:  Survey available at
[9] Christopher McKagen, Columbia Representative’s Bill Would Ban Johnsonville’s Use Of License Plate Readers, available at
[10] Id.
[11] Julia Angwin and Jennifer Valentino-Devries, New Tracking Frontier:  Your License Plates, available at
[12] ACLU, Automatic License Plate Readers: A Threat To American’s Privacy, available at
[13] See Jones, 132 S. Ct. at 950 (citing Katz, 389 U.S. 347, 347 (1967)).
[14] See Jones, 132 S. Ct. at 951.
[15] Id (quoting Soldal v. Cook County, 506 U.S. 56, 60 (1992)).
[16] See California v. Greenwood, 486 U.S. 35, 43-44 (1988).  Available at
[17] See United States v. Knotts, 460 U.S. 276, 281 (1983). Available at
[18] See Kyllo v. United States, 533 U.S. 27 , 36 (2001).  Available at,21&as_vis=1
[19] See Smith v. Maryland, 442 U.S. 735, 742 (1979).  Available at

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