Many of the people who are involved in the process of criminal defense in Pennsylvania are doing so in the city of Philadelphia, and that is mainly because this is the largest, most densely populated region in Pennsylvania, therefore, it's going to have the highest crime rates. If you are charged with a criminal case in Philadelphia then you will most likely go through processing and arraignment in the Municipal Court's Criminal Division as this is where every adult arrest in the city is supposed to be processed. If you are going on trial for a felony, then ultimately you will go on to another courthouse, but if you are going to face a criminal offense for a misdemeanor whose sentence is not going to be more than five years, your trial will take place in the criminal division.
Many people who have found themselves involved in a criminal defense in Pennsylvania were there because they did not realize that just because they may not have fired the weapon or may not have done the "really bad stuff", if they were present they could be tried as either a co-conspirator or an accessory. Even if you are not involved on the crime and you aid the criminal after the fact by providing them with shelter or food while they were trying to hide from the police you could still be tried as an accessory to a felony after the fact. Sometimes people who never meant to commit a crime find themselves facing some severe criminal charges.
If you are found guilty after going through a trial for criminal defense in Pennsylvania, and you think that it is a wrongful conviction, then you can work with your attorney to have the decision hopefully reversed on appeal. This is where the case is tried again mainly on the merits of the testimony and evidence to determine if the person found guilty was subjected to proper investigation techniques and that nothing was railroaded by the previous judge and District Attorney. These courts are known as the Appellate Court, and they specifically have jurisdiction to overturn a verdict that has already been rendered in another court case. Because of the ever-evolving state of physical evidence there is usually a lot of small things that might cause a case to be reversed on appeal.