Although we pretend otherwise, much of what we do in the law is guesswork.

In fact, much of the so-called wisdom that has been handed down to us about the workings of the legal system, and the criminal process in particular, has now been undermined by experience, legal scholarship and common sense. What I have listed below are some of the reasons to doubt that our criminal justice system is fundamentally just.

Here are just a few examples:

1. Eyewitnesses are highly reliable.
   This belief is so much part of our culture that one often hears talk of a “mere” circumstantial case as contrasted to a solid case based on eyewitness testimony. In fact, research shows that eyewitness identifications are highly unreliable, especially where the witness and the perpetrator are of different races. Eyewitness reliability is further compromised when the identification occurs under the stress of a violent crime, an accident or catastrophic event—which pretty much covers all situations where identity is in dispute at trial. In fact, mistaken eyewitness testimony was a contributing factor in more than a third of the wrongful conviction cases contained in a database maintained by the National Registry of Exonerations.

2. Fingerprint evidence is foolproof.
   Not so. Identifying prints that are taken by police using fingerprinting equipment and proper technique may be a relatively simple process, but latent prints left in the field are often smudged and incomplete, and the identification process becomes more art than science. When tested by rigorous scientific methods, fingerprint examiners turn out to have a significant error rate [PDF]. Other types of forensic evidence have also been called into question by recent scholarship.

3. Human memories are reliable.
   Much of what we do in the courtroom relies on human memory. When a witness is asked to testify about past events, the accuracy of his account depends not only on his initial perception, but on the way the memories are recorded, stored and retrieved. For a very long time, it was believed that stored memories were much like video tape or film—an accurate copy of real-word experience that might fade with the passage of time or other factors, but could not be distorted or embellished. Science now tells us that this view of human memory is fundamentally flawed. The mind not only distorts and embellishes memories, but a variety of external factors can affect how memories are retrieved and described [PDF].

4. Innocent people never confess.
   Innocent people confess with surprising regularity. Harsh interrogation tactics, a variant of Stockholm syndrome, the desire to end the ordeal, emotional and financial exhaustion, family considerations and the youth or feeble-mindedness of the suspect can result in remarkably detailed confessions that are later shown to be utterly false.

5. Police are objective in their investigations.
   In many ways, this is the bedrock assumption of our criminal justice process. Police investigators have vast discretion about what leads to pursue, which witnesses to interview, what forensic tests to conduct and countless other aspects of the investigation. Police also have a unique opportunity to manufacture or destroy evidence, influence witnesses, extract confessions and otherwise direct the investigation so as to stack the deck against people they believe should be convicted. Indeed, there are countless documented cases in which innocent people have spent decades behind bars because the police manipulated or concealed evidence.

6. Guilty pleas are proof of guilt.
   Many people, including judges, take comfort in knowing that an overwhelming number of criminal cases are resolved by guilty plea rather than trial. Whatever imperfections there may be in the trial and criminal charging process, they believe, are washed away by the fact that the defendant ultimately consents to a conviction. But this fails to take into account the trend of bringing multiple counts for a single incident—thereby vastly increasing the risk of a life-shattering sentence in case of conviction—as well as the creativity of prosecutors in hatching up criminal cases where no crime exists and the overcriminalization of virtually every aspect of American life. It also ignores that many defendants cannot, as a practical matter, tell their side of the story at trial because they fear being impeached with prior convictions or other misconduct.

7. Prosecutors play fair.
   The Supreme Court has told us in no uncertain terms that a prosecutor’s duty is to do justice, not merely to obtain a conviction. It has also laid down some specific rules about how prosecutors, and the people who work for them, must behave—principal among them that the prosecution turn over to the defense exculpatory evidence in the possession of the prosecution and the police. Most prosecutors play fair, but not all of them do [PDF]. And when they don’t, it can lead to disastrous consequences.

8. Long sentences deter crime.
   In the United States, we have over 2.2 million people behind bars. Our rate of approximately 716 prisoners per 100,000 people is the highest in the world [PDF], over 5 times higher than that of other industrialized nations like Canada, England, Germany and Australia. Sentences for individual crimes are also far longer than in other developed countries. For example, an individual convicted of burglary in the United States serves an average of 16 months in prison, compared with 5 months in Canada and 7 months in England. It is expensive for US taxpayers, as the average cost of housing a single prisoner for one year is approximately $30,000 [PDF]. A 20-year sentence runs into something like $600,000 in prison costs alone.

We in the United States have committed to a system of harsh sentencing because we believe that long sentences deter crime and, in any event, incapacitate criminals from victimizing the general population while they are in prison. It’s true that the United States is enjoying an all-time low in violent crime rates, which would seem to support this intuition.

But crime rates have been dropping steadily since the 1990s, and not merely in the United States but throughout the industrialized world. Our intuition about harsh sentences deterring crime may thus be misguided. We may be spending scarce taxpayer dollars maintaining the largest prison population in the industrialized world, shattering countless lives and families, for no good reason.

This article is an edited excerpt of Alex Kozinski’s earlier article “Criminal Law 2.0,” which was published at 44 Georgetown Law Journal Annual Review of Criminal Procedure, at iii (2015).

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