The goals and values of the United State's Criminal Justice System rest on a few core principles. While these are not a perfect representation of what happens in the real world, they are nonetheless the standard that the system strives to maintain.
First, anyone accused of or charged with a crime is, from the court's perspective, innocent. "The burden of the proof lies upon him who affirms, not he who denies" - as the Latin saying goes (Ei incumbit probatio qui dicit, non qui negat). They must be proven guilty of the crime beyond a reasonable doubt, by the prosecution, before being considered guilty.
Similarly, the legal rights of the accused must be protected. This is commonly referred to as Due Process, which seeks to ensure that laws are not vague and are applied fairly to the accused. In addition, the accused is to be notified of their charges and have an opportunity to be heard before actions are taken to deprive them of their life, liberty, or property.
The Sixth Amendment spells out many of the rights of which those charged with a crime are entitled, such as having "the Assistance of Counsel" for their defense. This means that a defense attorney can be hired by the accused or provided by the state in the event they lack the resources to procure legal representation on their own.
The accused are also entitled to be judged fairly by impartial jurors without influence or interference from outside sources. The process must also take place openly in a venue that is publicly accessible to ensure that all involved are treated fairly and equitably. According to the principles of the United States Criminal Justice System, all are to be considered equal before the law.