US juries get verdict wrong in one of six cases: study

So much for US justice: juries get the verdict wrong in one out of six criminal cases and judges don't do much better, a new study has found.

And when they make those mistakes, both judges and juries are far more likely to send an innocent person to jail than to let a guilty person go free, according to an upcoming study out of Northwestern University.

"Those are really shocking numbers," said Jack Heinz, a law professor at Northwestern who reviewed the research of his colleague Bruce Spencer, a professor in the statistics department.

Recent high-profile exonerations of scores of death row inmates have undermined faith in the infallibility of the justice system, Heinz said.

But these cases were considered relative rarities given how many checks and balances - like rules on the admissibility of evidence, the presumption of innocence and the appeals process - are built into the system.

• "We assume as lawyers that the system has been created in such a way to minimize the chance we'll convict the innocent," he said in an interview.

• "The standard of proof in a criminal case is beyond a reasonable doubt - it's supposed to be a high one. But judging by Bruce's data the problem is substantial."

The study ...

..., which looked at 290 non-capital criminal cases in four major cities from 2000 to 2001, is the first to examine the accuracy of modern juries and judges in the United States.

It found that

• judges were mistaken in their verdicts in 12 percent of the cases while
• juries were wrong 17 percent of the time.

More troubling was that

• juries sent 25 percent of innocent people to jail while
•  the innocent had a 37 percent chance of being wrongfully convicted by a judge.

The good news was that the guilty did not have a great chance of getting off. There was

• only a 10 percent chance that a jury would let a guilty person free while
• the judge wrongfully acquitted a defendant in 13 percent of the cases.

But that could have been because so many of the cases ended in a conviction:

• juries convicted 70 percent of the time while
• the judges said they would have found the defendant guilty in 82 percent of the cases.

The study did not look at enough cases to prove that these numbers are true across the country, Spencer cautioned.

But it has provided insight into how severe the problem could be, and has also shown that measuring the problem is possible.

• "People have to have some faith in the court system. We have to know how well our systems are working," Spencer said in his suburban Chicago office.

• "We know there are errors because someone confesses after the fact or there's DNA evidence," he said.

• "What's the optimal trade-off given that juries ultimately will make mistakes? ... Are those balances something society is okay with?"

Spencer's study does not examine why the mistakes were made or which cases ought to be overturned.

Instead, he determined the probability that a mistake was made by looking at how often judges disagreed with the jury's verdict.

• "If they disagree they can't both be right," he explained.

Spencer found an agreement rate of just 77 percent, which means a lot of mistakes were being made.

Spencer hopes to find funding for a much larger study whose results could be representative of the overall system.

Finding a solution will be much harder to do than quantifying the problem, Heinz warned.

• "The sources of the errors are quite resilient to correction," he said.

• "They have to do with all sorts of biases and the strong presumption of guilt when someone is arrested and brought to trial."

The study will be published in the July edition of the Journal of Empirical Legal Studies.