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What is a Daubert Motion?

Posted by Dmitry Gorin | Sep 04, 2023

If you're charged with a crime and federal prosecutors intend to bring in expert witnesses to testify against you, your federal criminal defense attorney may file a Daubert motion to keep potentially substandard testimony from being presented to the jury.

Named after the landmark Supreme Court case, Daubert v. Merrell Dow Pharmaceuticals, the Daubert motion is a critical tool to challenge and potentially exclude scientific evidence that the prosecution wishes to present at trial.

Daubert Motion in Federal Criminal Cases
A "Daubert motion" is used in federal criminal cases to challenge expert witness testimony.

Also called a "Daubert Test" or "Daubert Standard," is a method courts use to determine whether or not expert testimony should be admissible at trial. This standard in criminal cases can be raised when the defense lawyer or prosecutor believes the other side is using faulty information to prove their point.

When an expert witness is called to testify at trial, their opinion could significantly impact the jury's perception. This makes it crucial that their theories are backed by evidence rather than their personal beliefs.

Under the Daubert Standard, the trial court will consider several factors to determine whether the expert's methodology is valid, such as if the technique or theory in question can be or has been tested.

The court will also consider whether it has been subjected to publication and peer review, known or potential error rate, existence and maintenance of standards controlling its operation, and if it has attracted widespread acceptance within a relevant scientific community.

Simply put, the “Daubert Standard” provides a system for a trial court judge to assess the reliability and relevance of expert witness testimony before it is presented to a jury. Let's take a closer look below.

Daubert Motion - Explained

A Daubert motion is a specific type of legal motion filed by a party in a lawsuit, typically the defendant, to exclude the testimony of an expert witness or the presentation of unproven scientific evidence.

What is a Daubert Motion?
Federal Rule of Evidence 702 requires that expert testimony consist of specialized knowledge.

The motion is based on the premise that the expert's methods are not scientifically valid or relevant to the particular case. This standard came forth because Federal Rule of Evidence 702 requires the following:

  • That expert testimony consists of scientific, technical, or other specialized knowledge and
  • That it legitimately helps the judge or jury understand the evidence or issues raised in the criminal case.

Suppose one side wants to challenge expert witness testimony in a criminal case. In that case, they would file a "Daubert Motion," which forces the other side to prove that the expert is basing their opinion on legitimate scientific principles.

Before the Daubert case, the Federal Rules of Evidence effectively allowed courts to decide if an expert witness was qualified to testify, while the jury would decide whether their testimony was credible, commonly known as the "Frye" standard.

However, the 1993 Supreme Court ruling in Daubert changed this by putting more responsibility on judges to ensure that only reliable scientific evidence could be presented at trial. The ruling established a set of criteria for evaluating scientific evidence, now known as the "Daubert" standard, including the following:

  • Whether the theory or technique has been tested,
  • It can be and has been subjected to peer review and publication,
  • It has a known error rate, and
  • Is generally accepted within the relevant scientific community.

When Is It Filed?

A Daubert motion is typically filed before trial and may be based on information found in discovery documents, including expert witness reports or papers. In some instances, it can also be filed after the trial begins.

How Does It Differ from a Motion in Limine?

Many legal experts consider the Daubert motion a type of motion in limine in that it seeks to exclude evidence from jury review.

However, a motion in limine is generally filed before the trial begins ("in limine" means "at the threshold") and covers any evidence that can unfairly prejudice the case.

A Daubert motion can be filed before or during the trial and seeks to exclude expert testimony presenting questionable scientific evidence.

What Is the Rationale Behind Filing One?

A Daubert motion is not merely a procedural step; it's a strategic move that defense attorneys employ to challenge the validity and reliability of questionable expert testimony or scientific evidence presented by the prosecution.

A successfully argued Daubert motion can have profound implications on the outcome of a case. The defense can effectively undermine the prosecution's case by discrediting specific scientific methods or experts.

For instance, if a court finds a forensic scientist's DNA analysis method unreliable, the evidence may be excluded, bolstering the defendant's position.

What Are the Criteria for Granting a Daubert Motion?

When a Daubert motion is filed, the judge will schedule a "Daubert hearing" where both sides can present arguments regarding the expert testimony without the jury present.

The judge will then apply the Daubert standard to determine whether the testimony should be admissible. As noted, the Daubert standard includes a broad set of criteria, but we can summarize these criteria with the following factors, which include (but are not limited to):

  1. Empirical Testing: Has the scientific theory or technique undergone rigorous testing? Is there a known or acceptable error rate?
  2. Peer Review and Publication: Has the scientific community scrutinized the theory or technique through peer reviews and publications?
  3. Widespread Acceptance: Does the relevant scientific community generally accept the theory or technique?
  4. Relevance and Applicability: How well does the scientific evidence align with the facts of the case? Is it pertinent to the issues at hand?

Beyond these criteria, the court also evaluates whether the evidence gathering followed due process. For instance, a blood sample's improper storage could render subsequent test results unreliable, hence inadmissible.

What Happens if a Daubert Motion is Granted?

If the judge grants a Daubert motion, the expert testimony or scientific evidence may not be presented before the jury.

What Happens if a Daubert Motion is Granted?
If a judge decides to grant a Daubert motion, the expert testimony can't be presented to the jury.

The ruling also prevents the prosecution from presenting similar evidence throughout the trial. Depending on the gravity of the excluded evidence, granting a Daubert motion could signal an impending acquittal for the defendant.

In some cases, however, a judge may reject the motion and allow the potentially questionable evidence to be submitted. In such cases, the defense must counter any rebuttal testimony or evidence that might invalidate the expert's conclusions.

For a review of your case by our federal criminal defense attorneys, you can contact us by phone or through the online contact form. We serve clients throughout the United States on federal criminal matters. Eisner Gorin LLP has offices in Los Angeles, California.

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About the Author

Dmitry Gorin

Dmitry Gorin is a licensed attorney, who has been involved in criminal trial work and pretrial litigation since 1994. Before becoming partner in Eisner Gorin LLP, Mr. Gorin was a Senior Deputy District Attorney in Los Angeles Courts for more than ten years. As a criminal tri...

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