lawyer bio
Keep in mind that the law is always changing, and some articles may include outdated references or caselaw. Always check with an attorney before acting on what you read. For more, please visit the Disclaimer page
You are reading: Katz is out of the Bag: Katz’s Weaknesses & the Rapidly Emerging Technology of Today and the Future, (2005)
Click here to return to the Articles Page, or return to the Law Office of Robert Keates homepage

Katz is out of the Bag:
Katz’s Weaknesses & the Rapidly Emerging Technology of Today and the Future. 

Robert Keates                                                                                     Spring, 2005


B.            General Use Doctrine
The court’s general use doctrine is a well intentioned judicial tool that lacks the flexibility required to adequately account for changing technologies.  In Kyllo, Justice Scalia recognized the need for a rule that would apply across time, producing different results at different times.   By adhering to Scalia’s solution, the courts have inadvertently created a timebomb, allowing privacy protections to expire as use of the technology becomes widespread.
Few of the technological tools discussed above are in wide use by law enforcement, let alone the general public.  As Harlan mentioned in Katz, use of technology without a warrant must also be utilized by the general public to be outside of the Fourth Amendment’s scope.   Law enforcement’s use of a thermal imaging unit without a warrant violates Fourth Amendment protections now, but once thermal imaging units become mainstream in the public, the device will cease to violate any privacy rights.  The same result would occur when gun detectors are introduced to the public as a safety deterrent, or facial recognition systems are sold by home security companies for use at a homes front door.  Under the general use doctrine, the privacy afforded to the public from these items would become a nullity, allowing invasive government use without a warrant. 
The courts general use doctrine is at best, a temporary solution; new technology is becoming available to the public faster and cheaper than ever before. Take computers for example.  In 1993, a 486CPU desktop computer had a suggested retail price of $3,500.   Seven years later, a 1GHZ desktop computer cost $2,750, and today a Pentium IV laptop computer, immensely faster than a 486CPU, routinely sells for $1000.   Facial recognition software could easily follow suit, with over 500 companies presently researching and offering products for sale. Many home use facial recognition software systems are available for under $100.
The public use doctrine could be construed as a cooling off period for technology, allowing society to become accustomed to the types of invasion of privacy, and to take precautions.   Technology not only offers devices that can intrude on privacy, but also counter-intelligence devices designed to defend privacy.  Once people began to use binoculars, society purchased shades for their windows.  Electronic surveillance can be detected by sweepers or bug detectors.   White noise and acoustic noise generators can effectively block electronic listening devices.   It is easy to imagine thermal heatproof wall covers, holsters that can block gun detector rays or bags that claim to seal off and contain all molecules.
However, once a technique such a thermal imaging has become accepted, more advanced models would still be outside of the Fourth Amendment if preventative measures are inadequate.  Assume that after heatproof wall covers are designed, a later model of thermal detection is developed, specifically designed to circumvent the heatproof wall.  Would this latest model still be considered in general use as a generic thermal detection unit, or would the entire class of thermal detection units have to be categorized? 
The question then becomes ‘when’ technology is actually considered within the mainstream public use.  There are several difficulties posed by this question, including that devices may be unconstitutional in its early days of development, but constitutional later.  Imagine that in the year 2015, 5% of the population owns a gun detector system mounted above the front door to their home.  The weapon detector is capable only of detecting guns.  If discovered, images of the gun are relayed to a computer screen inside the house. Assume that in 2017, the police have used the system randomly on the streets, and after making several arrests, the gun detectors are challenged in court but deemed not to violate Fourth Amendment protections because they are not in general use.  The state appeals and the case comes to trial in 2018. Now 18% of the population has gun detectors mounted at their homes.  After the appeals court affirms the lower courts decision, the state again appeals.  After more litigation, the Supreme Court grants certiorari in 2022.  By then, 25% of the population has gun detectors not only mounted above their doors, but on small binoculars in their cars or briefcases.  Should the Supreme Court use the date of the first arrest, and therefore a 5% general use rate, or should they use the current 25% general use rate to evaluate the case?   Should the court take into account the general use rates during the first trial, filing of appeals briefs, oral arguments, or the appellate court’s decision?
The question becomes increasingly complex when more advanced models emerge to combat counter-intelligence devices.  Image that 2023, the Supreme Court rules that gun detectors are in general use, and therefore officers must obtain a warrant to use them.  By this time, companies are offering special holsters that camouflage a firearm, rendering them indistinguishable to the gun detectors.  In 2025, gun detector firms develop a new model of the device, which can not only reveal guns that have been camouflaged, but can reveal all the contents within a person’s pockets.  General use of gun detectors, regardless of the model, is now at 40%.  Are the new model gun detectors also constitutional, or must gun detectors be divided into classes based on capabilities.  If the latter is true, this cyclic process becomes more complex with each technological advance.  Now the data must be re-evaluated, taking into account the percentage of the population utilizing the older model of gun detector.  What if there are not two models, but five, or ten, all with different capabilities.  Where should courts begin to evaluate.  And where should they end? What happens if gun detectors are superseded by a new technological advance, rendering the gun detector obsolete?   As the public acclimates themselves to the newer technology, does the gun detector fall out of general use and sink back into the protection of the Fourth Amendment?
The general use doctrine presents more questions than answers.  Although the court had the right idea to create a rule that could shift with emerging technology throughout the years, the general use doctrine is far too inflexible.  Workable solutions and suggestions are difficult to conceive.  These will be addressed in the Conclusion.

Orin S. Kerr, The Fourth Amendment and New Technologies: Constitutional Myths and the Case for Caution, 102 Mich. L. Rev. 801, 873 (2004).

Katz, 349 U.S. at 361.

  James "Agg" Rolfe, TimeWarp Computer Prices, August 4, 2004, at

Moore’s Law, originating in computer science, hypothesizes that the latest computers on the market each year have doubled in speed from the previous years models.  This has occurred each year since invention, slowing down only recently, where they double in speed every 18 months.

Rolfe, TimeWarp Computer Prices, supra note 251.

Kerr, supra note 249, at 874.

Kerr, supra note 249, at 874.




Warning: include_once(): https:// wrapper is disabled in the server configuration by allow_url_include=0 in /home/keatzlw5/public_html/ on line 111

Warning: include_once( failed to open stream: no suitable wrapper could be found in /home/keatzlw5/public_html/ on line 111

Warning: include_once(): Failed opening '' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/keatzlw5/public_html/ on line 111