Do you really want to know how the jury pool got fixed?
Answer: most people cannot afford to go on jury duty. Government employees continue to receive their salary while on the jury. So those working in the private sector plead "financial hardship," while the government employees don't get that excuse.
Jury pay needs to be tied to the juror's actual earnings in some fashion.
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Poohbah, can you see the conflict of interest here?
Police made the arrest, as they do in most cases.
Their lives would be affected by their rulings while on a jury.
Any government employee, not just a policeman, has an inherent conflict because he knows what his employer wants, and he has sound reasons to give more weight to the prosecution's case. He lives and works with the people who represent the government, and has both financial and social reasons to find the defendent guilty.