Casey’s case: What psychology says about Anthony’s acquittal.

Casey Anthony

Credit: Red Huber/AP Photo

Everyone seemed to think Casey Anthony would be found guilty of murdering her 2-year-old daughter Caylee.

They all thought wrong.

In light of Anthony’s recent murder acquittal, plenty of people have wondered (either angrily or with genuine confusion) how a jury could possibly acquit Casey Anthony when her guilt seemed so apparent to the general public. As it turns out, several legal and psychological characteristics that have historically influenced the outcomes of jury trials may be able to clarify this bewilderment.

ResearchBlogging.orgWhy Was This A Shock?

One of the most notable aspects of the Casey Anthony verdict has been the extreme outrage over her acquittal (see the first link listed under ‘Additional Links’ below for some statistics on this). Some of this can be attributed to raw emotionality; however, there are two factors that do make the acquittal seem particularly surprising from a legal and psychological standpoint.

1. Caylee Anthony’s Age. Trials are more likely to result in a conviction when the victim is a child.

2. The Jury Was ‘Death-Qualified’. When the death penalty is on the table (as it was in this case), jurors are screened to make sure they are willing to impose the death penalty; if a juror is unwilling to do so, he/she is excluded. Jurors who are ‘death-qualified’ also tend to be more likely to make premature decisions about defendants’ guilt, be more convinced of these initial decisions’ correctness, and end up voting guilty. Considering the fact that all of the jurors on the Casey Anthony case had to have been death-qualified, it’s particularly surprising that they did not lean towards conviction.

Yet despite these two ‘shocking’ factors, there are a glut of reasons why Casey Anthony’s acquittal may not be so surprising after all.

Evidence Strength

When it comes to juries, they really care about evidence – and they really care about eyewitnesses. Despite the scientifically proven unreliability of eyewitness testimony, most jurors don’t know – or care – about this minor detail. The sheer number of prosecutorial witnesses is correlated with the likelihood of conviction in most jury trials; however for Casey Anthony, even though the prosecution had upwards of 300 witnesses (as of the list that I saw, though I could be mistaken as there are countless “witness lists” floating around on the internet), none of them could provide an eyewitness account of the murder itself.

Furthermore, general strength of evidence is the single strongest predictor of conviction in most criminal trials. Not only was there no eyewitness testimony, but any available forensic evidence was considered questionable (see the next section on the “CSI Effect” for more discussion on this). Strong, scientific evidence simply was not available (or perceived as such); 300+ character witnesses and all of the suspicious behavior in the world may not make a difference when none of those witnesses can report a time or cause of death.

The “CSI Effect”

There has been a particularly cynical theory traveling around legal circles known as the CSI Effect, which asserts that the widespread popularity of forensic television shows (such as CSI and Law & Order) has distorted jurors’ ideas of what constitutes “convincing evidence.” The reality of forensic evidence collection simply doesn’t line up with its portrayal on primetime television; TV shows often depict crime scenes as DNA, fingerprint, and bodily fluid havens, with evidence processing taking mere hours. In reality, it’s often difficult to obtain conclusive forensic evidence from a crime scene, and even when obtained, the data can take weeks or months to process and analyze. Even when forensic evidence is available, laypeople overestimate how conclusive this evidence ends up being. Whereas investigators on TV often assert that a fingerprint “matches” a given suspect, real forensic technicians can’t make this definitive of a claim; they can only really say that the evidence and the given suspect are “associated.” To an unknowledgeable juror, an assertion like this doesn’t quite live up to their televised expectations of what “convincing evidence” should look like.

A quick demonstration of the CSI Effect from the TV show Futurama

However, this effect has not gone uncontested. Many (such as NYU psychologist Tom Tyler) also argue that the preponderance of primetime crime shows should actually lead to more convictions; anyone who regularly watches these shows knows that they usually wrap up in an hour with a satisfying, guilty verdict, and the few shows that depict acquittals are largely unsatisfying. It’s entirely possible that a jury accustomed to guilty verdicts and the satisfaction of ‘solving a case’ would be less likely to acquit a defendant as a result of watching too much Law & Order. As a result, the ‘CSI Effect’ may suggest that the jury was biased by primetime perceptions of what ‘strong forensic evidence’ should look like, and this would have helped Casey Anthony out – but it could also suggest that the jury would be much more likely to want her ‘episode’ to end with a satisfying conviction.

Evidence Admissibility

Many trials involve evidence that is deemed inadmissible, and Casey Anthony’s was no exception. Juries are often influenced by inadmissible evidence despite explicit instructions to ignore it, particularly when said evidence benefits the defendant’s case. Anthony’s defense team argued that she had been sexually abused by her father, a circumstance which trained her to lie frequently and prompted her to cover up her daughter’s accidental drowning. There was even speculation that convicted kidnapper Vasco Thompson would be called to the witness stand to testify that he had spoken several times with Anthony’s father, George. The evidence was later deemed inadmissible, and Thompson later denied any connection with George Anthony, but this probably didn’t make much of a difference; Casey Anthony may have benefited from these claims, even though the evidence was contested.

Negative Publicity

The effect of negative pretrial publicity seems obvious; the more exposure the jury has to negative press (which is usually against the defendant), the more likely they are to convict. However, it’s not quite this straightforward.

First of all, it’s important to note that although the Casey Anthony case has been covered sporadically in the media since 2008, the press has been mostly quiet for the past 3 years. The jury was sequestered when the trial began, meaning they were not exposed to the upswing in negative publicity that the rest of the country has been receiving; that’s 2 months of biasing within the population to which the jury was simply not subjected. This is possibly why so many people in the general population firmly believed that Casey Anthony was guilty, while the jury clearly did not see it that way.

Secondly, the lack of strong evidence in the Casey Anthony case has already been discussed; however, it’s worth mentioning that evidence strength has an impact on the effect of pretrial publicity. When the prosecution has a particularly weak case, any bias from negative pretrial publicity essentially vanishes. As the jury was present in the courtroom to witness the weak evidence firsthand, any pretrial biases were likely diminished in a way that the general public’s was not.


Plenty of people have thrown out speculation that Casey Anthony was acquitted in large part because of her race. There are two racial factors that matter in murder trials: the race of the defendant and the race of the victim. Death penalty sentencing is significantly more likely when the defendant is non-white and the victim is white; by this logic, many have argued that being white helped Casey Anthony avoid the death penalty. Of course, racial bias doesn’t necessarily impact every individual trial; after all, O.J. Simpson was an African-American defendant accused of murdering a white female. In this case, race may have played a minor role, but it was probably not a significant factor…especially since Casey’s daughter was white as well.


We don’t like to think that physical appearance can affect something as serious as a murder trial, but looks count. In one research study, mock jurors were more lenient on an attractive defendant than an unattractive one; a separate study showed that jurors were almost twice as likely to acquit an attractive defendant than an unattractive one. There’s no denying the fact that when it comes to how we imagine an alleged murderer ‘should look,’ Casey Anthony certainly falls on the prettier end of the spectrum – and this may have biased the jury in her favor, whether they realized it or not.

How Might The Jury Have Played A Role?

We don’t know anything personal about the jurors for this particular case; however, juror characteristics can influence trial judgments, and it’s not inconceivable to think that certain attributes of the jurors themselves may have been a factor.

  • Similarity. Overall, jurors are more likely to be lenient towards defendants that are similar to them in some meaningful way. For example, jurors are less likely to convict defendants if they are of the same gender or race, or if they come from a similar socioeconomic background. If the majority of jurors were white, female, or from the same social class as Casey Anthony, it may have played a role in her acquittal. However, it would probably have hurt Casey Anthony if many of the jurors were mothers; whether or not Casey Anthony committed murder, many have scorned her for an apparent lack of maternal compassion. Many mothers on the jury would likely try to psychologically distance themselves from her in an attempt to protect their own maternal self-esteem, thus viewing her as increasingly dissimilar.
  • Authoritarianism. Jurors who are rigid, socially conventional, conservative, or generally dogmatic by nature are more likely to convict defendants and also more likely to impose longer sentences. If the jurors in the Casey Anthony trial were particularly liberal and/or open-minded, this may have helped her out.
  • Previous Experience. Jurors who have already served on a jury are more likely to convict future defendants. If all (or most) of Casey Anthony’s jurors were rookies, this may have made an acquittal more likely. However, this isn’t the only possible effect of prior experience. There’s also evidence that jurors who have served on a previous trial tend to evaluate current evidence based on how it compares to evidence from prior trials. If jurors had previous experience sitting on juries where there was more conclusive forensic evidence, they may have been more likely to maintain reasonable doubt regarding Anthony’s alleged guilt.


Many have been shocked by the Casey Anthony verdict, but upon a second look, there are a number of factors that made this acquittal more likely. There were no eyewitnesses and there was a distinct lack of strong, forensic evidence, and the “CSI Effect” suggests that this may have been a particularly glaring omission for many jurors. Casey Anthony is a pretty girl, and her race probably didn’t hurt her odds of acquittal. Her defense team introduced evidence that, though ultimately inadmissible, may have helped create some nagging thoughts of reasonable doubt for many of the jurors. Despite a rush of negative pretrial publicity, the lack of strong prosecutorial evidence likely diminished any effect that the negative press may have had on the jurors. Furthermore, we don’t know anything about the makeup of the jury, but it would not be surprising if a significant number of them were white, female, from a similar socioeconomic background as Anthony, liberal, and first-time jurors (or returning jurors who had previously participated in a trial with particularly strong forensic evidence).

Additional Links

The Online Reaction to the Casey Anthony Verdict by Christina Warren at Mashable

The CSI Effect: The Truth about Forensic Science by Jeffrey Toobin at the New Yorker

Casey Anthony and the CSI Effect by David French at National Review Online

The Devil Wasn’t Dancing When The Casey Anthony Verdict Came In by Douglas Keene at The Jury Room

There has been so much coverage of the Casey Anthony trial on blogs and in the news that it would be futile to try and link to them all. However, above are some interesting links on the trial and its legal/psychological aspects, including some more articles on the CSI Effect, and below are several of the academic references that informed this post, most notably the first (Devine et al., 2001). If you have written a blog post or article on the Casey Anthony trial, please link to it in the comments!

This post was chosen as an Editor's Selection for

Devine, D., Clayton, L., Dunford, B., Seying, R., & Pryce, J. (2001). Jury decision making: 45 years of empirical research on deliberating groups. Psychology, Public Policy, and Law, 7 (3), 622-727. DOI: 10.1037//1076-8971.7.3.622

Adler, F. (1973). Socioeconomic factors influencing jury verdicts. New York University Review of Law and Social Change, 3, 1-10.

Bowers, W. J., Sandys, M., & Steiner, B. (1998). Foreclosed impartiality in capital sentencing: Jurors’ predispositions, guilt-trial experience, and premature decision making. Cornell Law Review, 83, 1476-1556.

Izzett, R.R., & Leginski, W. (1974). Group discussion and the influence of defendant characteristics in a simulated jury setting. The Journal of Social Psychology, 93, 271-279.

Loftus, E.F. (1979). Eyewitness testimony. Cambridge, MA: Harvard University Press.

MacCoun, R. (1990). The emergence of extralegal bias during jury deliberations. Criminal Justice and Behavior, 17 (3), 303-314. DOI: 10.1177/0093854890017003005

Myers, M. (1979). Rule departures and making law: Juries and their verdicts. Law & Society Review, 13 (3), 781-797. DOI: 10.2307/3053186

Nagel, S., & Weitzman, L. (1972). Sex and the unbiased jury. Judicature, 56, 108-111.

Tyler, T. (2006). Viewing CSI and the Threshold of Guilt: Managing Truth and Justice in Reality and Fiction The Yale Law Journal, 115 (5). DOI: 10.2307/20455645

8 responses to “Casey’s case: What psychology says about Anthony’s acquittal.

  1. These are all plausible suggestions and I commend the post. But as a recovering attorney who has tried murder cases and lesser crimes, I can explain this one pretty easily: there are specific elements to each crime and ALL must be proven beyond a reasonable doubt. Jurors almost always take the instruction on elements and beyond a reasonable doubt seriously.

    The state severely overreached in this case and had it focused on lesser charges that could be proven, CA would have been convicted of a less serious (but still serious) charge such as felony child abuse. Classic prosecutorial overreach.

    • Cris,

      You have no idea how much I am absolutely kicking myself right now! I was about to direct you to a section of my blog post, until I remembered that I took it out in the very final edit. It was a section I’d titled “What The Prosecution Did Wrong,” and I took it out to avoid making my post seem biased. In the section, I discussed some other psychological research showing that juries are significantly more likely to convict a defendant of any given charge when there are more charges on the table; in fact, even when convicting for a lesser charge, they are likely to impose more serious sentences (sometimes even on par with the sentences that would be expected for the more serious charges). I then argued that the biggest mistake the prosecution made was not adding charges such as (non-aggravated) child abuse or child neglect, as CA likely would have been convicted. Now I wish I’d left that section in!

      On another note, I believe you when you say that juries generally take the requirement for “reasonable doubt” very seriously. However, with a case as emotionally charged at this one, many (including myself) were surprised that the jurors did not find reasons to claim that they had no reasonable doubt, even in the absence of strong forensic evidence. After all, motivated reasoning and biased processing are powerful beasts. Because of this, I was more interested in exploring some of the psychological variables that could have led the jury to make a surprisingly rational decision given the high emotional charge of this particular case, rather than examine the prosecutorial mishaps (especially since I have no legal background).

      Thank you for your comment!

  2. Melanie — you could of course just add that section! Just kidding. It is a great post and I appreciate the insights. Another fruitful avenue of inquiry would be to ask why the prosecutors messed up so badly on the issue of lesser charges. I suspect they became emotionally involved in the case and this clouded their judgment.

    • Oh, and I’d believe you 100%. Prosecutors are human, after all, and just as vulnerable to biases/emotionality as the rest of us. That’s a really great insight! I never thought to question how psychological variables may have impacted the prosecution’s handling of the case in the first place. I suspect some of the logic there would probably apply to several other cases with legal teams who had suboptimal approaches to the trial/charges as well – emotional bias is very likely to be a common thread.

  3. Pingback: News » Blog Archive » Editor’s Selections: Creativity, Casey Anthony, and Crying

  4. I am using this site as a source for a paper I am writing. Who is the author??

    • Glad to hear that this site could be helpful for you!

      Information about me (the blog author) can be found on the “About Me” page; my full name is Melanie Tannenbaum. As for the specific information in the posts themselves, citations for all referenced research can be found at the bottom of every post.

      I hope you keep reading!

  5. GENDER!!! It’s an incredibly obvious factor that has solid support in studies.

    I don’t know how this wasn’t mentioned.

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