Right to trial by jury
This right is guaranteed in all criminal cases, as according to the 5th and 6th amendment. This applies to all courts except for appeals and administrative courts.
Jury trials are required for all offenses except if the defendant decides to forgo the choice of Jury trial. A non-jury trial is known as a bench trial.
Voir Dire
The selection for juries are made through a process called Voir Dire. This is where questions are asked from a random sample for finding biased individuals. Anyone who is removed for a reason regarding the potential bias that a person may have, That is called a “For-Cause Challenge”. For example, a person named Bob can be removed for being in the NRA. Alternatively, one that is arbitrary (and likely for biased reasons) is called a “Peremptory Challenge”.
Additionally, The pool for juries typically consists of people registered to vote in a jurisdiction. For federal (and state) jury trials, there is a requirement for a 12 person jury as there is clear federal regulation surrounding the size of juries, and states wish to standardize with the federal government. In order for a criminal court to find a person guilty, they need to find that everyone in the jury agrees that a person is guilty or not. If anyone disagrees with this verdict, they cannot be counted as guilty.
Personally, I would support trial by jury as it prevents tyrannical judges from inflicting punishment on people they do not personally like, and as a result, lead to more ability for people to get justice.