The trouble with the Jury system is that they are very susceptable to social mood. Look at where our country was during OJs trial in comparison to Scott Ps. Sure this does not explain everything, but it historically can be documented that in times of upswings in our growth as a country, the stock market goes up, people feel optimistic, and they tend to want to give powerful, celebrity icons the benefit of the doubt. However, in a wartime, unstable economic environment, there is a tendency to hang the bastards.
This is not to excuse anyone; it is only an observation.