People who followed the televised trial of Casey Anthony seemed to be convinced that she was guilty of killing her child–yet the jury, which heard the case, found her Not Guilty.

How could this happen?

In my 30+ years of trying criminal cases, both as a prosecutor and defense lawyer, I can tell you that it’s rare, but it does happen.  Why?  How can a seemingly guilty person (like O.J. Simpson) “get off?”  Here are seven possible reasons why this happens, including the Casey Anthony case.

Reason #1  The burden to prove guilt is on the government, not the accused

The key to understanding why guilty people sometimes “get off” is to remember what happens in a trial.  It’s not the balancing of two sides, each with their own version of the facts, in order to determine who’s correct.  For you parents, think of your kids getting into a fight with each other.  You intervene and listen to both sides and, like an arbitrator, decide who’s guilty and who’s innocent.

A criminal trial is much different.

Remember that every accused person is presumed innocent all during the trial and that will only change if the jury decides to do so.  That means even after all the evidence and been presented to the jury and they’re deliberating, the accused must still be presumed innocent.

The question the jury wrestles with is whether or not the evidence presented by the government during the trial has convinced all twelve jurors beyond a reasonable doubt that the presumption of innocence should be removed and the defendant found guilty.  They don’t balance the prosecutor’s evidence against the defendant’s evidence to determine which tips the scales the most.

The accused doesn’t have to present any evidence and may not even say a word–as  Casey Anthony chose not to testify in her trial.  In American law, the jury cannot “hold this silence against” an accused person and think she’s hiding something.  The burden to prove guilt remains with the prosecutor.

In 90+% of trials, the prosecutors meet this burden and juries find defendants guilty.  But sometimes, they don’t as in the Anthony or OJ Simpson cases.

Reason #2  Prosecutors don’t have enough evidence.

In the United States, once a case has been investigated, the prosecutors have the authority to charge a person with a crime.  Before they do so, the prosecutor must believe they have enough evidence to convince a jury.  Sometimes, they don’t.

For instance, in the Casey Anthony trial, the prosecutor’s case was built on circumstantial evidence–that’s because no one directly witnessed the death of the child.  Circumstantial evidence is as valid as direct but it makes for a more difficult case for a prosecutor.  It’s like seeing smoke–you’d think there’s a fire, but until you actually see the fire itself, you can’t say beyond a reasonable doubt that a fire exists.

Any good prosecutor will try their best to assemble enough evidence through investigation, witnesses, and forensic proof, to convince a jury, but sometimes that’s still not enough–which is probably what happened in the Anthony trial.

I’ll continue looking at the reasons why this could happen in my next post.