In light of the Eric Gardner and Micheal Brown Grand Jury outcomes. I wanted to know what % of Police Officers are actually indicted by a Grand Jury.
I found some interesting charts that may give additional context:
As there are few government data on the subject of police complaints, it is hard to come by a definite answer. However, FiveThiryEight.com examined several studies which found that around 40% of complaints against police officers resulted in legal action, and of those complaints that did result in legal action, 33% resulted in a conviction and 12% in an incarceration.
This is lower than the conviction rate for the normal population, in which 68% of felony defendants who aren't police officers are convicted, and 48% are incarcerated.
For Grand Jury indictments specifically: while grand juries result in indictments approximately 100% of the time, grand juries will tend to indict much less frequently if the defendant is a police officer. In 2010, of 162,000 federal grand juries, only 11 declined to indict. While there are few good data on nation-wide grand jury investigations of police officers, some specific locations have been studied, and in those locations, grand juries have tended to refuse to indict police officers. In the 81 grand jury investigations of police shootings in Dallas between 2008 and 2012, only 1 resulted in an indictment.
The hard data does not exist to answer the question, but analysis of what data is available points towards it being quite the anomaly for a police officer to be indicted.