Like the infamous OJ criminal case, Casey Anthony's acquittal has disappointed many and led to calls for changes in the justice system. These people miss the point.
Disappointment is when reality exceeds expectations. Disappointment can lead to frustration, which can lead to rash decisions. Anyone who expected a conviction expected too much of our system. It is not geared towards readily convicting the accused.
Following centuries of experience, Western criminal justice systems are designed to limit the power of government prosecutors from obtaining automatic convictions, primarily by allowing for jury trials. Also, the prospect of having to convince a jury deters over-zealous police and prosecutors from bringing and pursuing potentially bogus yet damaging criminal charges. That prospect also leads to most cases being resolved via plea agreements, without which the over-crowded criminal justice system would cease to function.
Casey Anthony elected to have a jury trial, a constitutional right at least. The jury heard the case and made its decision. Appellate courts are built to make sure the rules were followed, not to second guess acquittals. Experienced criminal defense lawyers know that juries are impossible to predict. We've all won cases we "should have" lost, and lost cases we "should have" won.
When people know the outcome of a trial ahead of time, it is called a show trial, and many countries still put on show trials. Rather than lament the lack of a conviction in Ms. Anthony's case, we should appreciate the fact that our time-tested justice system worked exactly the way it was designed.