The beyond a reasonable doubt standard of proof: Juror understanding and reform
| Author | Olivia K. H. Smith |
| DOI | http://doi.org/10.1177/13657127221114498 |
| Published date | 01 October 2022 |
| Date | 01 October 2022 |
| Subject Matter | Articles |
The beyond a reasonable doubt
standard of proof: Juror
understanding and reform
Olivia K. H. Smith
University of Wyoming, USA
Abstract
The beyond a reasonable doubt (BARD) standard of proof is the foundation of criminal court
proceedings in the U.S. However, both empirical and field studies alike demonstrate that jurors
do not correctly interpret and apply the standard. Misinterpretations of the standard can have
large implications for criminal defendants on trial. Thus, researchers and legal scholars have
attempted to clarify the standard through various methods (e.g. quantification, reasoning, lin-
guistic simplification, and procedural changes), and some of these methods have promising fea-
tures. The purpose of the current review is to provide a comprehensive overview of these
proposals and determine future directions for researchers and legal practitioners.
Keywords
juror, proof, standard, criminal, reasonable doubt
Within the U.S. court system, there is a legal term known as the “burden of proof.”Often, scholars
describe burden of proof as the “duty to persuade”(McBaine, 1944), referring to the process of convin-
cing factfinders (i.e. jurors) of whether a presented fact is true. This process of persuasion must convince
jurors of a defendant’s guilt or liability to a certain standard or degree, known as the “standard of proof.”
Although this process may seem straightforward, complications arise due the various standards of proof
and their meanings (McCauliff, 1982).
There are three primary standards of proof: (1) proof beyond a reasonable doubt, (2) preponderance of
evidence, and (3) clear and convincing evidence. In criminal proceedings, the standard of proof is beyond
a reasonable doubt (BARD), and the burden of proof rests with the prosecution (Cleary et al., 1972).
Although the law does not indicate an exact percentage (Weinstein and Dewsbury, 2006), scholars typ-
ically conceptualize BARD as a threshold of 90% certainty, emphasizing the “innocent until proven
guilty”mentality (McCauliff, 1982; Picinali, 2009; Simon, 1969; United States vFatico, 1978). In
other words, when jurors are at least 90% certain that the defendant committed the crime, they should
find the defendant guilty (King, 2020). In civil cases, when punishment is typically monetary rather
Corresponding author:
Olivia K. H. Smith, University of Wyoming, 1000 E University Ave., Laramie, WY, USA.
Emails: osmith3@uwyo.edu; olivia.khsmith@gmail.com
Article
The International Journal of
Evidence & Proof
2022, Vol. 26(4) 291–308
© The Author(s) 2022
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/13657127221114498
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than incarceration, the burden of proof is much lower. For example, the plaintiff only has to prove their
case by either a preponderance of evidence, which typically represents a 51% threshold (i.e. more likely
than not to have occurred; Brook, 1982) or clear and convincing evidence, which typically represents a
70% threshold (Vance, 1996). Consequently, the BARD standard is the highest standard of proof
required in the U.S. court system, and thus, the focus of the current review.
History of the BARD standard
The BARD standard dates back to the 12th and 13th century (DeLoggio, 1986). Early writings on BARD
did not explicitly refer to “reasonable doubt,”but instead used terminology such as “moral certainty,”
meaning a high degree of certainty, but not complete certainty (Shapiro, 1986). In the earliest forms
of the criminal standard of proof, legal professionals conceptualized the standard as a threshold equiva-
lent to “almost certain,”and by the 18th century, BARD was the standard for most criminal trials
(DeLoggio, 1986). Although BARD has been an established standard in the legal system, its meaning
lacked clarity from early on, and the court did little to proactively rectify this confusion. In fact, most
efforts for clarification of BARD came during trial when it became evident that further explanation
was required. One of the earliest attempts to explain the BARD standard at trial occurred during the
case of Commonwealth vWebster (1850). At trial, the judge defined the BARD standard as, “…It is
that state of the case, which, after the entire comparison and consideration of all the evidence, leaves
the minds of jurors in that condition that they cannot say they feel an abiding conviction, to a moral cer-
tainty, of the truth of the charge”(Shapiro, 1986: 175). This definition soon became the most common
definition in court following analysis by the Supreme Court (Commonwealth vWebster, 1851), and in
1970, the Supreme Court officially established BARD as the standard of proof for criminal trials (In
re Winship, 1970). However, soon after its establishment, issues arose on whether BARD was a self-
evident concept or if judicial instructions were needed for proper application. These issues made their
way to the U.S. Supreme Court.
The BARD standard in the U.S. Supreme Court
The U.S. Supreme Court heard several landmark cases about the ambiguity of the BARD standard in the
1990s, and Justices were forced to make decisions regarding an appropriate definition. The defendants in
these cases claimed that the definition of BARD presented to jurors violated their constitutional due
process rights. For example, in Cage vLouisiana (1990), Tommy Cage was convicted of murder and
received a death sentence. However, in an appeal to the Louisiana Supreme Court, Cage argued that
the language used by the judge when explaining the BARD standard could have resulted in jurors inter-
preting the degree of doubt needed to acquit as more than what is required under BARD. Specifically, this
contested language included terminology such as “substantial doubt”or “grave uncertainty”to describe
reasonable doubt (Cage vLouisiana, 1990). Louisiana’s Supreme Court decided the case against Cage,
but the U.S. Supreme Court overturned the decision in favor of Cage.
Sandoval vCalifornia (1994) represents another landmark U.S. Supreme Court case regarding the
BARD standard. In this case, the judge’s instruction equated reasonable doubt to “not a mere possible
doubt”depending on “moral evidence,”and “moral certainty”was used to indicate the degree of certainty
needed to convict. In addition to this difficult terminology, the full instruction was linguistically complex,
with multiple clauses per sentence, various prepositional phrases, and ambiguous language (Horowitz,
1997). Aside from the linguistic issues, Sandoval argued that the use of the terms “moral evidence”
and “moral certainty”relayed to jurors an inaccurately high level of doubt needed to acquit. In addition,
Sandoval argued that “moral evidence”opened the door for extralegal factors (e.g. personal prejudices or
moral codes) to impact the jury’s perception of BARD. The U.S. Supreme Court acknowledged that the
292 The International Journal of Evidence & Proof 26(4)
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