Digital Patrol, Part 2 - Technology and Communications -

Digital Patrol, Part 2

How to get digital images admitted as evidence



Steve Ashley | From the January/February 2006 Issue Tuesday, January 31, 2006

Digital cameras might sound like a great idea for law enforcement use for many reasons, including no film to buy, store, process or waste; easy storage of images on a computer; and no need to produce expensive reprinted enlargements.

But, and it's a big but, what about image admissibility issues? It's possible defense attorneys will challenge your digital images as unreliable, implying that it's too easy to alter digital images and, therefore, the court shouldn't admit them into evidence.

Of course, challenges to evidence admissibility are nothing new. An entire body of court rules, both federal and state, as well as case law, has evolved to deal with the issue of admissibility. In fact, any defense attorney worth their fee will always consider challenges to evidence. In this regard, challenges to photos are to be expected, and digital photos are no exception.

The problem: Although the legal framework for determining evidence admissibility has evolved over centuries, and the guidelines for admissibility of photographic evidence have developed similarly over many decades, digital images remain relatively new. Serious questions arise as to whether the existing admissibility requirements can apply to this new thing: the digital photograph.

In Part One of this feature ("Digital Patrol," September/October 2005, p. 46), I reviewed the ways you can adapt digital photography to fit your law enforcement needs. Part Two tackles the issue of admissibility and offers guidelines to increase the likelihood your images will be admitted.

Digital is Different

While digital image prints may look the same as film prints, the development process of each is altogether different. A digital image is nothing more than a computer file, and all information captured by computers is binary in nature. This means that, at its most basic level, computer information is made up of a series of "bits." Each bit is actually a little switch that's either open (which equates to a digital value of 0) or closed (a digital value of 1). These digits (hence the term "digital") combine in many different ways to make up all the different types of data that computers manage. The data is gathered into files, and the way in which it's gathered will determine the file's format. Thus, data gathered in a certain way becomes a word-processing file, while data gathered in a different way becomes a digital-image file.

When you take a picture with a digital camera, light enters through the lens, just as it does in a traditional film camera. But the similarity ends there. The light photons strike a light-sensitive cell that converts them into a series of 1's and 0's, thereby digitizing the image, and the camera's electronics save the information in a file within the camera.

This process is significant because the rules of evidence have evolved to deal with analog data, such as documents and photographs, and not digital data. Digital cameras represent a relatively new way of creating evidence, and the images they produce pose a whole new set of questions for the courts to consider.

Rules of Evidence

Most officers are familiar with the basic rules of evidence; that is, they know what they must do to ensure evidence will be admitted. Officers realize they must take care with anything seized as evidence to preserve it in as close to its original state as possible. They know they must document the possession of each item from the moment it's found until the moment it arrives in court. They know this evidentiary chain must be complete, with no gaps, and that anyone and everyone who had possession of the evidence along the chain must be prepared to act as a witness and to testify under oath that the evidence was preserved during the time it was in their possession. In fact, they know that they, or the primary officer on the case, must also testify regarding the chain of evidence, and that the item presented in court is in fact the same item seized at the crime scene.

This process of evidence preservation is one of the first and most important things an officer learns, and it applies to photographs of evidence and of the scene, as well as physical items. Photos of the scene become evidentiary items themselves, subject to all the same requirements as if they were a knife, a rock or an item of clothing picked up on scene.

In our society, we tend to accept photographic evidence as representative of what it purports to show. Although most people realize traditional photos can be manipulated in a darkroom, generally they conclude it's not easy to do, and that unless the manipulator is highly skilled, it's almost impossible to alter a photograph in a way that cannot be detected. The courts recognize this, and a body of evidentiary law has sprung up around the fact that two primary things must be established for a photograph to be admissible: relevance and authenticity.

The first of these is usually a legal question, which holds little bearing on this discussion. The second, authenticity, is more problematic. While some courts have occasionally excluded traditional photos because they could not be authenticated, generally this is not the case as long as testimony shows the photo in question accurately portrays the scene it's intended to portray. In fact, it's not usually necessary for the photographer to testify as long as the chain of custody for the film remains intact and documented, and that someone who can reasonably be expected to know can testify on the authenticity of the depiction.

The courts also generally accept a print as admissible under the best-evidence rule, as opposed to requiring that the actual negative be introduced into evidence (the negative is usually considered a sort of "super original" that can be examined if necessary).

When considering photo manipulation, images can be altered in two general ways. One is to alter the entire image in some way, such as lightening an underexposed or dark image, to better view detail. The other is to alter certain items in the photo, such as inserting objects that were not in the original scene or shifting the position of objects. The courts generally allow the first type of manipulation as long as it's documented, and have almost always excluded the second.

The problem with digital images is that while early methodologies to manipulate them were complicated and awkward, requiring expensive computers and specialized software, that's no longer the case. Additionally, would-be photo manipulators needed significant skill to use this early equipment and software, and that's also no longer the case. The wide availability of affordable computers and inexpensive, easy-to-use (frequently automated) software has made the manipulation of digital images very easy for even the casual computer user.

Originally, courts began managing the admissibility of digital images under the business-records exception to the hearsay rule, but that's not a good fit either. The business-records exception is based on the fact that business records generally can be relied upon because they are systematically kept in the course of business, usually to generally accepted standards. Therefore, any aberration in business records should be fairly obvious. The problem: With today's equipment and software, digital images can be so easily manipulated this systematized process doesn't apply.

Getting Images Admitted

The key to ensuring your digital images will prove admissible lies in a multi-pronged approach:

Develop a standardized routine for taking, storing and managing your digital images.

Take digital photos using the default, automatic settings on your digital camera. That way you won't have to record settings and data for every photo you take. If you do alter a setting, carefully document the change and why it was necessary.

Make sure the camera's calendar and clock are set to the proper date and time. (Note: Don't have your camera set to superimpose the date and/or time onto the actual photo; that could obscure details in the image. The camera will apply the date and time stamp to the digital file created when the photo is saved.)

Make the first picture a shot of a data sheet or board containing the appropriate information regarding the scene date, time, complaint number, address, photographer name, etc. just as with a film camera.

Set your camera to save its images to a removable memory card. When you finish photographing your scene, remove the card and replace it with a clean one until you can offload your images from the card to your computer. Then you can reformat and reuse the card. Note: In some jurisdictions, you may be required to maintain the card and its original images for trial check with your district attorney.

Avoid deleting bad shots. Keep all images to avoid the accusation that you deleted shots that would exonerate the suspect.

When you offload your images, do so using a program that will allow you to write the images directly to a non-rewritable CD. Set your software to close-and-finalize the disk so that nothing can be added to it. Use CDs with serial numbers (usually located around the hub in the center). Make two CDs in the same manner. Record the serial numbers in your original report.

Carefully store the CDs in a secure location, such as your property room. Log them in just like any other piece of evidence.

When it's time to print photos, use one of the CDs, keeping the other as a secure master. Use a program that will allow you to print directly from the CD to your printer. If you manipulate the images in any way, such as lightening or darkening, carefully note the settings used and the reason the manipulation was necessary. Print one image as it appeared originally, before manipulation, to clearly establish the need for the manipulation.

Designate a particular person to manage your digital images, whether it's the original officer who took the photos or a specific individual who will manage all images for your department. If you have the available personnel, designate one individual.

Keep an accurate log of all activity involving your images, from the moment they're taken until they are presented in court.

Capture all of the above points in a written policy.

Final Thoughts

While following these guidelines doesn't absolutely guarantee your images will be admissible, they should give you a firm foundation for offering them into evidence. Remember, the real issue is not whether the image is exactly the same but whether the substantive depiction of the scene has been altered (e.g., removing an object or placing a vehicle in a different location in the frame, manipulations possible with both traditional and digital imaging methods).

The admissibility of photographic evidence relative to its true representation of the scene or object is more a measure of the testimony of the photographer or investigating officer than a question of the technological possibility of manipulation.


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Steve AshleySteve Ashley is a retired police officer, and an active trainer and risk manager. Contact him at


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