07: Expert Witnesses; What is Possession?


Assignment 04 due date pushed to next Tuesday.

Next Thursday (a week from today, 23 February) is our first midterm.


(Much of the following is based on or a direct quote from the readings.)

Court system

To a first (very) approximation, the purpose of the court system is to resolve disputes related to law in a predictable way. Disputes may be between individuals, or between entities (including the government); disputes may be over contracts, or civil or criminal law, or common law.

A trial (or "case") is a judicial proceeding in which facts of a controversy are presented in a technical, legal form for decision making. The object of a case is to enforce rights and remedy wrongs between the plaintiff (initiator of a case) and the defendant (the party who responds).

Through a proscribed set of procedures (pre-trial, trial, post-trial; criminal vs civil), trial courts do three things:

  • fact finding: which witnesses are credible; who said what to whom; when actions occurred; etc.
  • law finding: which rules of law are applicable to the facts and claim
  • law application: decide the dispute on the basis of the facts and law

Expert witnesses help primarily with the first function.

Expert witnesses

A qualified expert may give his opinion to help the court understand evidence, or to establish a fact in issue.

The expert witness performs two primary functions: 1) the scientific function — collecting, testing, and evaluating evidence and forming an opinion as to that evidence;and 2) the forensic function — communicating that opinion and its basis to the judge and jury. A general rule of evidence is that witnesses may only testify to what they have personally observed or encountered through their five senses.

There are five categories:

  1. Lay people: common sense and life long experience
  2. Technician/examiner: limited and concentrated training, applies known techniques, works in a system and taught with the system [e.g., investigator and supervisors (observers and viewers)]. The technician is generally taught to use complex instruments (gas chromatographer, infrared spectrophometer, mass spectrophotometer) or even "simple" breath alcohol testing equipment as "bench operators," who have only a superficial understanding of what the instrument really does, and how the readout is generated. "Bench operators," who qualify as expert witnesses, are not competent to explain the instrumentation used unless it is established that they received the training and education necessary to impart a thorough understanding of the underlying theories.
  3. Practitioner: material and information analysis and interpretation.
  4. Specialist: devoted to one kind of study or work with individual characteristics.
  5. Scientist: conducts original empirical research, then experiments to verify the validity of the theory; designs and creates instrumentation and applied techniques; is published in own field with peers; and advances his field of knowledge.

A consulting expert is a person who has been retained or specifically employed in anticipation of litigation or preparation of trial, but who will not be called at trial. The identity, theories, mental impressions, litigation plans, and opinions of a consultant are work product and protected by the attorney-client privilege.5

A testimonial expert is retained for purposes of testifying at trial. The confidentiality privilege is waived and all materials, notes, reports, and opinions must be produced through applicable discovery proceedings. If an expert relies on work product or hearsay as a basis for their opinion, that material must be disclosed and produced through discovery.

When can an expert testify?

Judge is gatekeeper: Under Rule 702, the task of "gatekeeping", or assuring that scientific expert testimony truly proceeds from "scientific knowledge", rests on the trial judge.

Relevance and reliability: This requires the trial judge to ensure that the expert's testimony is "relevant to the task at hand" and that it rests "on a reliable foundation". Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 584-587. The Judge must find it more likely than not that the expert's methods are reliable and reliably applied to the facts at hand. (More on this below.)

Scientific knowledge = scientific method/methodology: A conclusion will qualify as scientific knowledge if the proponent can demonstrate that it is the product of sound "scientific methodology" derived from the scientific method.

Illustrative Factors: The Court defined "scientific methodology" as the process of formulating hypotheses and then conducting experiments to prove or falsify the hypothesis, and provided a set of illustrative factors (i.e., not a "test") in determining whether these criteria are met:

  1. Whether the theory or technique employed by the expert is generally accepted in the scientific community;
  2. Whether it has been subjected to peer review and publication;
  3. Whether it can be and has been tested;
  4. Whether the known or potential rate of error is acceptable; and
  5. Whether the research was conducted independent of the particular litigation or dependent on an intention to provide the proposed testimony.

Qualifying an expert

Whether a witness is qualified as an expert can only be determined by comparing the area in which the witness has expertise with the subject matter of the witness' testimony.The standard of review and criteria for expert witness testimony has been codified by three cases, commonly known as the "Daubert Trilogy."

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

  1. The expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
  2. The testimony is based on sufficient facts or data.
  3. The testimony is the product of reliable principles and methods; and
  4. The expert has reliably applied the principles and methods to the facts of the case.

The voir dire examination qualifies an expert as relevant to a case. There is no specific test. Previous qualification as an expert on a related matter; CVs and resumes; etc.; ultimately, a party must establish the expert's competency and knowledge in the profession and field (not experience, education, or specialized training) subject to judicial approval, through an examination of the expert's credentials. The prospective witness is voir dired by the attorneys to determine their qualifications, and second, after the proponent of an expert witness asks questions of the witness to bring out the person's qualifications, the opposing attorney is allowed to voir dire the witness to bring out matters that might prevent his qualification as an expert. A witness is not deemed an expert until so qualified as such by the court.

Expert testimony

According to Federal Rule 26(2-b), before an expert witness can offer testimony, that person must provide a written summary opinion discussing the testimonial subject matter, substance of facts and opinion, basis for opinion, reports, a list of all publications authored by the witness in the preceding ten years, a record of all previous testimony including depositions for the last four years, disclosure statement, report signed by the expert, and disclosing attorney.

The disclosure statement generally includes the following information regarding the expert: qualifications; scope of engagement; information relied upon in formulating opinion; summary of opinion; qualifications and publications; compensation; and signature of both expert and disclosing attorney. Even though many states have adopted the Federal Rules of Civil Procedure, including Rule 26, parties should consult their own jurisdiction regarding rules of discovery and corresponding requirements.

Now, for something completely different.

What is possession?

In the US, it is a crime (both federal and state) to possess (and distributed, and receive...) images of child sexual exploitation, aka "Child Pornography" or CP. Do you possess something when it is "on your computer?" It depends.

This problem is easily identified but much less easily eliminated. The concept of "possession" seems intuitive when one thinks of a physical object: holding something, touching it, feeling it, having it physically present. In contrast, the concept of possessing something digital is more elusive. Looking at materials on a computer screen might seem more like window-shopping than physical interaction with the materials. However, surfing the Internet involves significant interaction and exchange of information between a user's computer and the web servers visited. Furthermore, the user retains a significant level of control over the information on the computer.

Finding, viewing, downloading CP

Users search for it. There are common terms; though it's also the case that CP might be mislabeled as adult pornography, and a user might inadvertently download it.

Is there a distinction between viewing and downloading CP? As the term is generally used, downloading an image requires a positive effort by the viewer to make a copy of the image in his hard drive. The person must instruct the computer to save or download the image and designate where it should store the image. Case law reveals that child pornography consumers use a wide variety of methods to download images.

Once saved to the computer's hard drive, the saved image becomes part of the data on the computer and can be accessed at any time without an Internet connection. In fact, even if the user decides not to look at an image ever again, the image will remain on the computer until the user takes affirmative steps to delete it.

But, the user may choose to view the images on the Internet without downloading them onto the hard drive. (Think YouTube, for example. You don't generally "download" the movies in the sense most people thing of downloading, though it's true the data does reside on your computer at least as long as need be to display it.)

But what about caching? As you probably know, computers can keep copies of even transient results to improve performance in various ways (why download it again, if it hasn't changed, for example?). Disk space is cheap, so web browsers tend to cache all sorts of things. But now, a file that was only "viewed" is stored on a user's disk!

This process occurs automatically, without any prompting by the user, any time an Internet user visits any website; thus, it is generally outside the control of Internet users. In fact, since there is no indication to the user that this process is occurring, a computer user could take full advantage of the Internet-surfing capabilities of his computer without ever learning what is happening behind the scenes.

Or consider email: what if you receive an unsolicited email containing CP? Do you possess it even if you haven't looked at it yet? What about if you delete it but it's kept in the "trash"?

What do courts say?

They often reach inconsistent outcomes despite having reviewed similar facts. Many courts consider factors such as control, seeking out the image, knowledge, and deletion without detailed explanations.

Courts often consider what the defendant can actually do with the image, usually focusing on the user's ability to retain the image on the screen, enlarge it, zoom in or out, copy it, print it, and ultimately delete it. That is, courts focus on the user's level of control over the image.

Courts have also looked at the defendant's assertive steps that led to the viewing or downloading of child pornography images. The courts' use of this test often arises in cases involving cache files, when the defendant argues that he did not intend for the computer to download the file. Indications of a user's actions to seek and obtain child pornography can include repeated visits to child pornography websites, a defendant's subscription to child pornography websites,91 and search terms related to child pornography.

Courts have applied knowledge as a factor in different ways. A common thread, however, is that any indication of knowledge by the defendant can be quite damning.

In a remarkably short opinion, the court in Commonwealth v. Gardner found that the defendant possessed child pornography based solely on a statement he made to investigators. The court held that an inference of knowledge could fairly be drawn where the defendant said, "'I don't have too much' in response to a question [Investigator] DePena asked [the defendant] about the presence of child pornography on his computer."

Courts often note a defendant's act to delete pornographic images. This factor often becomes significant as evidence of knowledge or control. In United States v. Bass, The defendant argued that he merely viewed images on the Internet and was ignorant of the computer's cache function. The court found that the jury could have inferred the defendant's knowing possession from his use of certain software to delete the files from his computer.

Courts synthesize these factors in different ways and reach different conclusions, especially about whether files in the cache constitute possession or not. US v Tucker and US v Romm exemplify this controst.

In US v Tucker, Tucker had a paid subscription to newsgroups where he viewed images; The defendant explained that he did not download the images onto his computer because he could always access more images. In fact, the defendant testified that he would often clear the cache after viewing images online, because he could access different images. Court (and on appeal) found that the required element of knowledge demonstrated by Tucker's volitional reach for the images and by his constant deletion of the cache. Essentially, because he "controlled" the cache, he possessed the images.

The Romm case is less clear. Romm "exercised control over the cached images while they were contemporaneously saved to his cache and displayed on his screen." The court explained that Romm's intentional searching and viewing of images, rather than an accidental pop- up, resulted in the images that were saved in the cache. The circuit court found control, and thus possession, over the image on the screen but convicted Romm of possession of—not that image—but the copy of that image in (the cached image). The reason behind this bizarre outcome is that Romm's control over the image on the screen occurred at the same time that cached image was created.

One possible solution

This situation is problematic for three reasons. First, it encourages willful blindness. Second, it would result in disparate treatment between those choosing to download images from a website and those with enough legal knowledge to understand that they should view the images without downloading them, even though both have the same control over the image while it is on their screen. Finally, courts' holdings become even more contradictory because many of those who know about a computer's cache are unlikely to be able to access it.

A large part of the problem underlying the confusion in this area of the law is the fact that courts do not tend to recognize the existence of two distinct possible approaches to possession of a digital image. Under the first approach—the "evidence of possession approach"—images stored in the cache are accepted as evidence of prior possession. Under the second approach—the "present possession approach"—the images in the cache are the objects actually being possessed. Under the "evidence of possession approach," the defendant is charged with possession of the image that was once on the screen, whereas under the "present possession approach" the defendant is charged with possession of the cached file itself.

Marin proposes a two-part test: "Dominion and control" and "seek to obtain"; goal here is to exclude any accidental downloads while including anyone who possessed (in the first sense) CP.