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75,268–273.ALIBIWITNESSES
An alibi,in its most basic form, is a plea that one was
not present when a crime was being committed. In prac-
tice, alibis can be considerably more complex than
a simple narrative story. In the criminal justice system,
alibis function as exculpatory evidence—a good alibi
should rule out the alibi provider as a potential suspect
in a case or provide reasonable doubt as to a defendant’s
guilt in a criminal trial. Psychological research into the
study of alibis is a relatively new area in psychology and
law. This entry summarizes some of the major findings
and introduces the terminology of the existing psycho-
logical literature.
It is unclear how alibis are used in the early stages of
criminal investigations, and the rules about how and
when alibi evidence can be used in the court system
vary greatly across jurisdictions. To function as excul-
patory evidence, alibis must contain both a believable
story and credible proof of the alibi provider’s where-
abouts. Psychology is in a unique position to study
alibis from both sides of the criminal process:Alibi
generation relies largely on the memory of alibi
providers and corroborating witnesses, and alibi evalu-
ationoccurs as the police, attorneys, and jurors decide
the exculpatory worth of the alibi. The study of alibi
generation can be informed by autobiographical mem-
ory research, and alibi evaluation can benefit from
deception detection and suspect interrogation research.
However, psychological research on alibis specifically
is still relatively new and has focused thus far on the
evaluation of alibis.
Alibis are evaluated according to their believability
by detectives, prosecutors, defense attorneys, and jury
members at different stages of the criminal process. For
an alibi to be judged believable, credible proof of the
alibi provider’s whereabouts is essential, and it can take
one of two forms: physical evidence and person evi-
dence. Credible physical evidence ties the alibi providerto a specific place and time; for example, an airline
boarding pass includes time and location information
and requires identification, making it highly unlikely
that someone other than the ticket holder would be able
to obtain the pass. The research to date has indicated that
physical evidence corroborating an alibi carries consid-
erable weight with alibi evaluators; mock jurors have
rated alibis with supporting physical evidence as more
believable than alibis without such evidence. However,
evaluators do not seem to differentiate between physical
evidence that might be easily fabricated, such as a cash
receipt, and evidence that is more difficult to fabricate,
such as a security video. Person evidence consists of
testimony by an alibi corroborator, or alibi witness, as
to the whereabouts of the alibi provider. Preliminary
research has shown that mock jurors are quick to
distinguish among alibi corroborators according to the
corroborator’s relationship to the alibi provider. Specifi-
cally, corroborators who could conceivably have a
motivation to lie for the alibi provider (such as a close
relative or a good friend) are viewed as less credible
than corroborators who have no relationship to the alibi
provider. Some research has suggested that having some-
one close to a defendant as an alibi corroborator could
be no better than having no alibi at all—mock jurors
voted guilty just as often when the corroborating wit-
ness was a motivated other as when the defendant had
no alibi defense at all.
Skepticism on the part of alibi evaluators may work
well when evaluators are dealing with fabricated alibis
offered by guilty defendants. However, difficulties may
arise when evaluators are faced with alibis offered by
innocent alibi providers. Innocent alibi providers could
potentially fall a victim to normal memory errors, such
as misremembering a date or time for a particular activ-
ity or failing to correctly recall their companions for a
particular day. Unlike in a normal recollection situation,
however, a normal memory mistake could look suspi-
cious in the context of a criminal investigation. Prelimi-
nary investigations into the strength of alibis produced
by innocent alibi providers suggest that people fre-
quently misremember their actions for a previous date
and have considerable difficulty producing any kind of
proof for their whereabouts. Anecdotal evidence from
past criminal cases suggests that evaluators may use a
weak alibi as incriminating evidence, which could be
especially worrisome for innocent alibi providers.
Continued research into the psychology of alibis
will shed additional light on how police detectives,
attorneys, and jury members deal with alibis in the14 ———Alibi WitnessesA-Cutler (Encyc)-45463.qxd 11/18/2007 12:41 PM Page 14