March 1, 2026
The Case Against Limited-Scope Warrants for Digital Evidence
" If someone is able to show me that what I think or do is not right, I will happily change, for I seek the truth, by which no one was ever truly harmed."
-Marcus Aurelius
I don’t work in full-time law enforcement anymore. I maintain professional relationships and credentials with the training academy, but my days of writing and executing search warrants are (likely) behind me. However, my current professional landscape has me still in the proverbial mix, particularly with regard to how high-tech investigations are being conducted all over the United States. While I’m not the one writing the warrants (or other legal demand), I’m very much in the role of reviewing the case files, assessing the merits of the documentation and advising attorneys on the efficacy (or lack thereof) of the investigation and ensuing digital forensic analysis in the criminal arena. Yes, the majority of the time, this means I’m working with criminal defense attorneys.
If you didn’t have the opportunity to watch Sean Harrington’s talk entitled “Rapprochement: Fuel for accelerating digital forensic investigations” at this year’s Magnet Virtual Summit (MVS), I highly recommend it for everyone, particularly those in the practice of high-tech criminal investigations for law enforcement. What Sean breaks down (and Jared Barnhart and I spoke on at Techno East in 2024) is the need for increased cooperation and understanding when law enforcement is dealing with “defense” experts, or as I like to re-define our work as “independent” experts. We’re all largely after the same things in our work – to find the truth. Yes, there are those who operate under a different approach and they are the exceptions, just like there are exceptions in every professional practice, and we as a community largely identify and know who they are. But by in large, we are all in the same boat – we want to find out what happened and ensure the right conclusions are made in order to put the correct bad guy away for the right reasons, ensuring completeness and accuracy in all the work that has been done.
Adding to the difficulty of this joint approach is the trend of limited-scope warrants (or other legal demands) in law enforcement and sometimes in the broader legals system. To be clear, I know this isn’t the fault of the investigator or examiner who is applying for, executing and adhering to the warrant. It’s the fault of an overly cautious mindset that has developed over time in many areas around the Country and it is not a positive development. Because I’m not applying for warrants anymore, I can only speculate about why this has been happening, but I suspect some sort of pro-privacy, pro-defendant approach is at least part of the reason.
The Limited Scope Warrant
The digital forensic methodology has traditionally prescribed that [paraphrased] we get all of the available data, make a verified copy of the entire dataset, then do an analysis on the copy for any & all relevant evidence. The issue that’s arisen over time with the limited scope warrant is the term “relevant”. If I’m working a CSAM case as an investigator, then the authorizing entity of my warrant says that I should only be looking for pictures and videos, right? I mean, it’s just an image case!
Likewise, if I’m working a case where we’re concerned about text messages, that’s all I should be looking at, right? After all, texts never get stored anywhere else or by any other means!
This approach is leading us down a path of incompleteness in our analysis. It’s setting up a scenario in which an independent (or defense) expert, who does have access to the entire dataset may be put in a position of calling out other relevant evidence that serves to invalidate the charges.
I’ve worked cases recently where law enforcement has only been allowed a limited-scope warrant and we ask for the data collected – all of it – in discovery, and are told that the scope of what was analyzed is limited, therefore that’s all we can have. That too is a horribly near-sighted approach, and it’s also probably not in the spirit of the rules of discovery. The natural argument is that everyone needs to be on an “even playing field”. If an investigator was only able to view certain evidence, then the opposing expert should also only be able to view that same evidence. Sounds “fair”, right? Not to the accused, it isn’t. Context matters in the course of a digital forensic analysis.
The Importance of Context
Frequent readers will no doubt take note of the mention of context in digital forensic analysis and investigations. I firmly believe this is an area where we – as a practice – are lacking in emphasis. Too often I see reports of “pump & dump” forensics where a trained analyst will simply copy and spit out a report of everything on a device for someone else – who is likely untrained and not as knowledgeable about digital evidence – to review. I understand this practice and why it happens, but I don’t think it’s a positive evolution. Any professional examiner should bristle at the notion of “the evidence speaks for itself.” If that were true, why does anyone need an expert in any case?
Context provides us many benefits depending on the type of case. Let’s look at three examples:
1) CSAM image cases. Very often what we see are pictures pulled off the phone or the computer device and presented in pre-trial discovery with the declaration [paraphrased], “We found the pics. Your guy is guilty. He should plead guilty.” While the existence of pictures is potential evidence of some sort of potential malfeasance, the nuances about where those pictures reside on the device and how they potentially got there and if the accused had access to them and if there is evidence the accused viewed them are all paramount to the case. Why? Read the criminal code section the guy is charged under, which undoubtedly states something like, “…knowing possession…” of the images, meaning there has to be evidence that he knew those images were on the device, which is all garnered through discovery of contextual information through digital forensic analysis. Are cached images or unallocated images “knowing” possession? Well, what’s our favorite answer in DF/IR… It depends!
2) Location data cases. These come up in varying forms, but I’ll concentrate primarily on the location data stored on a mobile device. In the “pump & dump” scenario, it’s very easy to provide all of the data from a device to an investigator with limited or no digital forensic expertise and tell them, “happy hunting!” and hope for the best. But when they find location data, the nuances about where that location data is stored and how it got on the device are crucial. I can search for any number of places on my iPhone and those locations may very well be stored in my phone, even though I never actually went to the locations. The source of the location data is key to determining if the device (not necessarily the person) traveled there.
… And don’t even get me going on historical cell site location data contextual importance. Actually, you can read about it here in an article published for NACDL in 2022.
3) Sexual Assault Investigations. I’ve written previously about the importance of collecting the data from both involved parties (accused and complaining witness) in sexual assault claims, but with the advent of limited-scope warrants, the importance of doing so – and articulating why it is important – seems crucial. Frequently, sexual assault claims arise between two known individuals, like boyfriend-girlfriend or date rape situations. And in the modern era, relationships are conducted via cell phones. Dating apps, hookup apps, meeting apps, texting, Snapchat, etc. Couples are almost exclusively meeting online and continuing their conversations on mobile devices throughout the course of their relationship. This means when a complaint of sexual assault is filed, there will be evidence on both devices of communications and other data of interest that led up to the alleged incident.
The two main issues that have arisen in many cases are, either courts/legal authority is not allowing the seizure/collection and analysis of the complaining witnesses’ device or they’re only allowing a limited scope analysis, usually the communications between the two people involved. What’s the problem with that? What if the complaining witness deleted portions of the conversation? What if they have a history of these types of complaints or potentially false allegations? What if they discussed the alleged incident and the reporting and surrounding events with someone else via text, like a close friend or relative? All of this is potentially relevant information. And it goes both ways – what if the accused has a history or has discussed these events with other people? It’s all extremely important and relevant contextual information.
And what if some of the text messages were stored via screen shot? Particularly of those screen-shot text messages have since been deleted from the messages themselves. A limited-scope warrant for text communications only may not permit discovery of this potentially valuable evidence.
Getting to the Point
Why does all of this matter in the context (see what I did there?) of our exploration of limited-scope warrants? If your warrant or legal demand only allows you to look for pictures, you’re lacking context. If it only allows you to look for location data and nothing more, you’re lacking context. If it limits you to conversations between only two people involved in an incident, you are likely missing important information. What’s more, you could be leaving out potentially exculpatory or inculpatory evidence that could serve to confirm or refute the accusations in the matter.
Context matters and the evidence does not speak for itself. And the push toward limited-scope warrants negates these two facts, which is why it is generally a negative development in the investigation of electronically-facilitated crimes/incidents and it is a direct affront to the scientific approach to digital forensic analysis.
If a crime scene analyst is collecting physical evidence at a scene pursuant to a search warrant, they likely don’t limit their collection to simply fingerprints or only DNA – they collect all of the available evidence, and focus the ensuing analysis on the evidence and the direction in which it points them. The presence of case-specific factors can certainly affect this. But if they were hyper-focused on one or two things and limited in that focus by their legal authority, we’d likely have many more innocent people in prison and many more bad guys out on the street.
We all want the same things – to put the correct bad guys away for the right reasons, supported by a thorough analysis of the evidence. Limited-scope warrants don’t allow for that, and it’s an approach we should all work toward removing as a factor in our cases.
About the Author:
Patrick Siewert served 15 years in full-time law enforcement and investigated hundreds of high-tech crimes to precedent-setting results, Patrick is a graduate of SCERS & BCERT and is a court-certified expert witness in digital forensics, mobile forensics and historical cell site location analysis. He has published dozens of articles and is cited in numerous academic papers. He was the Founder & Principal Consultant of Pro Digital Forensic Consulting, based in Richmond, Virginia (USA) and currently serves as Director of Digital Forensics and E-Discovery for a Nationwide (US) provider of DF/IR and e-disco litigation support services, while keeping in touch with the public safety community as a Law Enforcement Instructor in multiple disciplines.
Email: Patrick@ProDigital4n6.com
Patrick Siewert on LinkedIn: https://www.linkedin.com/in/patrick-siewert-92513445/
Patrick Siewert on X/Twitter : @RVA4n6
Pro Digital (old) blog site : https://prodigital4n6.blogspot.com/