Grand juries are a group of 12 to 23 people selected by a judge, who meet in secret to decide whether there is enough evidence to charge someone with a crime. Grand juries typically only see what the prosecutor presents to them and can indict someone based on that information alone. The use of grand juries in police brutality cases has become controversial because prosecutors and law enforcement are known to work closely together. It has been proven that a majority of the time, police officers will not get indicted when they should have, which is unfair to the victims. A fairer option would be to hold a preliminary hearing, however, there is still a long road ahead before this becomes a reality.
For more detail, read the easy-to-follow infographic.