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The Legal Implications of New Technologies in Criminal Defense Cases

Advances in technology are continually changing various aspects of our lives, from how we keep in touch with one another to how we go about our daily routines. Law enforcement and the criminal justice system are also constantly integrating new technologies into their operations, often in ways that can significantly impact defendants and their lawyers. Police officers are able to access vast amounts of information from their vehicles. Social media and other digital technologies provide them with a wealth of data that they can use in investigations, and that prosecutors can offer as evidence in court. Every criminal defense attorney should be aware of how these technologies can affect their clients’ rights. This article provides a summary of some new (and new-ish) technologies, along with some ideas about how they may affect the criminal justice system. 

How law enforcement can use new technology to collect evidence

Police departments and other law enforcement agencies have access to a wide range of new technologies for use in investigations. Some technologies help them identify suspects, while others allow police to track known individuals. Police may deploy devices to patrol or monitor areas without any connection to a specific crime. Many of these technologies are so new that courts have not had an opportunity to rule on their constitutionality.

Body cameras

Departments around the country have begun requiring or encouraging the use of body cameras by police officers while on duty. These are small recording devices that officers wear on the front of their uniforms to record their interactions. They can, at times, record instances of police officers violating people’s civil rights. They can also provide evidence that supports criminal charges.


Police may use drones to monitor neighborhoods or other large areas. Before drones became widely available, police had to rely on helicopters or airplanes for aerial surveillance. Drones are less expensive, use less fuel, and make far less noise. This makes them much more effective for surveillance but also raises constitutional questions.

The U.S. Supreme Court has ruled that aerial surveillance is not a warrantless search under the Fourth Amendment at least twice. California v. Ciraolo (1986) dealt with an airplane flying at an altitude of 1,000 feet, and Florida v. Riley (1989) involved a helicopter 400 feet off the ground. Drones can fly much lower and closer without drawing attention.

GPS tracking

A GPS tracking device, when attached to a vehicle, provides police with a record of everywhere that vehicle goes. The Supreme Court ruled in United States v. Jones (2012) that police must obtain a warrant to use this type of device.

Recognition technology

Recognition software can identify individuals based on multiple factors. Facial recognition is perhaps the most well-known example, but it is far from the only type. Another common type of recognition software claims to be able to identify people by voice. Few courts have addressed these technologies, and they raise numerous concerns. Many systems are prone to false positives, and they may tend towards furthering racial and other biases in policing. Data privacy may also be an issue.

Thermal imaging

Thermal imaging allows police to see differences in temperature inside a structure. In effect, it can allow them to see features like how many people are inside a building without actually being able to see inside. The Supreme Court set some limits on the use of thermal imaging in Kyllo v. United States(2001), which involved the use of the technology without a warrant to detect a marijuana growing operation.


Police have used various types of robots for different functions for some time. Much like drones, remote-controlled robots have become smaller and more affordable, so they have become more common.

Gunshot sensors

Acoustic gunshot detection equipment can record gunfire, estimate its source, and report this information to the police. Proponents of this type of technology claim that it is faster and more accurate than relying on witnesses to provide information. The equipment can produce false positives, however, and it cannot provide an exact source for gunfire sounds. It can also record other sounds, including human voices, which raises privacy concerns.

Cell tower spoofing

Mobile phones are able to maintain a connection to the cellular network by continually pinging nearby cell towers. Records of these pings can provide a rough record of that device’s location over time. Police sometimes use devices known as cell-site simulators, IMSI Catchers, or Stingrays to mimic or spoof a cell tower and collect pings from all nearby devices. This can tell them whether a particular person, or at least their phone is in the area. It can also give police information about everyone else in the area. Stingrays have been the subject of Fourth Amendment litigation, but no definitive caselaw exists.

Artificial intelligence

Artificial intelligence (AI) has gained recent media attention because of advances in areas like AI image and text generation. Police may use AI systems in their investigations, such as in  facial recognition software. Some police departments have tried a new form of AI called “predictive policing,” which is supposed to advise police on how to deploy resources based on numerous factors, including historical crime data.

AI can only learn based on the information provided to it. When an AI receives information about how police have acted in an area before, it is likely to make predictions based on whatever biases informed earlier decisions. Using AI to “predict” crime is therefore likely to perpetuate the same inequities that have plagued the criminal justice system.

How new technology can collect evidence for law enforcement

A massive amount of digital evidence about nearly everyone in this country is out there, often freely available to police, prosecutors, and others. Law enforcement does not have to do anything except collect, request, or subpoena this information.

Social media posts

One of the hallmarks of Fourth Amendment protection is that a person must have a reasonable expectation of privacy. Anything posted to social media is, essentially by definition, no longer private, even if a user limits how many other users can see it. Social media posts are also not limited to whatever information is visible. Metadata can provide information like when and where someone took a photo or video and where they were when they posted it.

Email, text, and direct messages

Unlike social media posts, email messages, text messages, and direct messages on services like Facebook Messenger or WhatsApp are not posted for the general public or a collection of followers. Law enforcement may still be able to access this information with a warrant.

Pictures and video footage from smart devices

People generally have a reasonable expectation of privacy with regard to the contents of their smartphones. The Supreme Court reached this conclusion in Riley v. California (2014), which held that police needed a warrant to search a person’s cell phone after their arrest.

Smartphones equipped with cameras are ubiquitous in many parts of the country. During events of any sort of significance, it is almost certain that someone is taking photos or recording video. Other “smart” devices, such as smart doorbells, are often also equipped with cameras. Police may be able to act based on images or footage that people have voluntarily turned over to them. 

Surveillance footage

As of late 2019, the United States had approximately 70 million surveillance devices in operation, or almost one camera for every four people. This includes home doorbell cameras, security cameras in and around private businesses, and surveillance cameras installed by local governments. Police often ask private businesses for copies of security footage if it might pertain to a crime that occurred nearby. Some U.S. cities have cut out the need to ask businesses for footage by installing networks of surveillance cameras.

Depending on where the cameras are located, they may raise privacy concerns. Another potential issue could be incorrect identifications, particularly if a camera’s video quality is poor.

Cell phone location data

As mentioned above, police can use cell tower data to determine the approximate location of an individual’s cell phone at a particular moment in time. This data can only demonstrate that a device was within a certain distance from a particular tower. Police therefore cannot use the data to pinpoint a device’s location, nor can they say for certain whether the owner of the device was in the same vicinity at the same time. Nevertheless, this type of data has become increasingly common in criminal cases. The Supreme Court ruled in Carpenter v. United States (2018) that the use of cell tower data is a search under the Fourth Amendment, and therefore requires a warrant.

Issues presented by digital evidence in criminal cases

Technology is constantly changing. As it does, it presents new challenges for criminal defense attorneys and their clients. The following are only a few such concerns.

Evidentiary issues

Much of the evidence produced by these new technologies is digital in nature. The ease of creating new digital information can be troubling in the context of criminal defense. At any moment, a defendant could produce evidence that the state could use against them. Social media posts might as well be part of the public record from their inception, but even text messages and emails can find their way into prosecution exhibits. Criminal defense lawyers should consider advising their clients to be careful what they post.

Many forms of digital evidence have a strange sort of permanence — as the saying goes, “the internet never forgets.” At the same time, digital evidence is quite ephemeral. Aside from physical media like a flash drive, there is nothing tangible that police and prosecutors can hand to one another. The chain of custody could be a concern. In the era of AI art and “deepfakes,” the authenticity of photographic or video evidence may also become a serious issue.

Constitutional issues

The legal system has probably barely scratched the surface of constitutional issues that may arise from various digital technologies. The use of AI in criminal investigations, for example, raises the question of how police determine probable cause based on analyses performed by computers. This may already be a concern with facial recognition software, and it is likely to come up in other contexts as well. 

The prominence of AI in criminal investigations may also raise Sixth Amendment questions. Criminal defendants have the right to cross-examine their accusers under the Confrontation Clause. What happens, though, when one of the accusers is a computer? This may sound like science fiction, but it might not be far off.

Access Resources for Professional Education

Criminal defendants deal with risks that are unlike anything a civil plaintiff might face in matters like personal injury. They need legal representation that can address how law enforcement uses new technologies. The National Trial Lawyers offers legal education programs that help criminal defense attorneys improve their knowledge and develop their skills. To learn more about the benefits offered by National Trial Lawyers, visit our website or contact us today.

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