Neuroscience and Federal Rules of Evidence 803(1): The Present Sense Exception

When I first learned the Federal Rules of Evidence in law school, I realized that they were grounded in practical insights into the way humans separate truth from error. While no one would claim that the FRE infallibly differentiates between true and false, these evidence rules do provide powerful guidance in the courtroom. I was not surprised to discover recently that one of the rules - the present sense exception - is consistent with current views of neuroscience.

Under the Federal Rules of Evidence, hearsay is generally not admissible as evidence in a U.S. federal court. Hearsay is basically the introduction by a witness of a statement made by another person in order to prove facts included in the assertion made by the other persion. Hearsay is inadmissible for a number of reasons, including that the person who made the original statement may not be available for cross-examination, so it is difficult to determine whether he/she was telling the truth.

One of the exceptions to the prohibition on use of hearsay is the "present sense impression" of FRE 803(1). According to the rules, a present sense impression is "A statement describing or explaining an event or condition made while the declarant was perceiving the event or condition, or immediately thereafter." An example of the present sense impression exception would be a case where someone is being approached by an attacker and says, "He has a gun," or some other factual observation.

Why do the Federal Rules of Evidence allow present sense impressions into evidence? Presumably because they are inherently reliable. If you are making audible observations during an experience, you are unlikely to lie about it. For example, if a dangerous individual were approaching you with a gun, you might says, "He has a gun," but it is very unlikely that you would say, "He does not have a gun."

Interestingly, the present sense impression exception only applies to statements made during an event or immediately (i.e., a few minutes) afterward. The law recognizes that if any significant amount of time elapses between the event and the stated impression, the impression becomes much less reliable.

This is in line with current views of how memory works. Over time, our minds change memories. We add details that we receive from sources other than our own sensory impressions, such as the statements of friends, news reports, and our own mental rethinking of an event. For an excellent discussion of this phenomenon, see Chapter 7 of the book Sleights of Mind (reference below).

Science often lags behind common sense, but in this case I think the science of the mind lagged behind the science of the courtroom (i.e., centuries of jurists' experience with the validity of certain types of testimony).

Sources

Federal Rules of Evidence, available at http://www.law.cornell.edu/rules/fre/rules.htm.

Macknick, Stephen L. and Susana Martinez-Conde. Sleights of Mind: What the Neuroscience of Magic Reveals About Our Everyday Deceptions. Henry Holt and Co.: New York. 2010.