The Commonwealth of Pennsylvania is comprised of 67 counties, each county has a district attorney and a court of common pleas. The district attorney is the chief law enforcement officer for the county; while, jurisdiction over crimes committed in a county falls to the court of common pleas. In Allegheny County, as in all counties in Pennsylvania, there is also a minor judiciary, called district justices or magistrates. The first steps of any criminal prosecution take place before the minor judiciary.

The following process describes how a prosecution would proceed through the court system in Commonwealth of Pennsylvania.

Step #1: CRIME COMMITTED

Step #2: POLICE NOTIFIED

Step #3: POLICE INVESTIGATE
The police investigation may include interviewing the victim(s), witnesses and/or suspects; collecting physical evidence; visiting, viewing, photographing and/or measuring the crime scene; identifying suspects through photo arrays or line-ups, etc.

Step #4: POLICE FILE COMPLAINT
Following a police investigation of an alleged crime, the police may initiate the criminal process by filing a complaint with the district justice or by making a warrantless arrest followed by the filing of a complaint. The complaint identifies the defendant, lists the crimes charged and contains a brief factual summary upon which the charges are based.

Step #5: PRIVATE COMPLAINT FILED
In the event the police decline to file a complaint, a private person is permitted to file a private complaint. However, an Assistant District Attorney must first approve the private complaint before it can proceed. Once approved, the process is the same as if the complaint had been filed by a police officer.

Step #6: SUMMONS OR ARREST WARRANT ISSUED
Once the complaint is filed, the presence of the defendant is secured voluntarily, by summons, or compelled, by arrest. The district justice will issue either a summons or a warrant of arrest, depending generally on the seriousness of the offense alleged. Less serious cases proceed with the issuance of a summons which provides notice of the defendant’s scheduled preliminary hearing.

Step #7: PRELIMINARY ARRAIGNMENT
An arraignment is the process by which the defendant is read specific charges against him. It is the first step in the criminal process after arrest. It is a brief hearing. All arraignments are conducted after the suspect is arrested and booked by law enforcement. An arraignment takes place only after the prosecuting attorney decides to file charges. The defendant must appear before the district justice for a preliminary arraignment. At this proceeding the defendant is provided with a copy of the complaint and advised of his rights; also at this time a preliminary hearing is scheduled, not less then three days but not more than ten days hence. The district attorney will not be represented at a preliminary arraignment.

Step #8: PRE-PRELIMINARY HEARING
This involves a meeting between the prosecution and the defense. Topics discussed normally include plea bargain opportunities, strengths and weaknesses of the prosecutions case, and intangible factors of the case, such as the defendant's character and past history.

Step #9: PRELIMINARY HEARING
The preliminary hearing is also normally convened before a district justice. At the Preliminary Hearing the Commonwealth must present a prima facie case, or in other words, they must show evidence that a crime has been committed and that the defendant is probably the perpetrator of that crime. The judge then determines whether sufficient evidence exists to send the case to the upper court for trial. The judge reviews whether there is probable cause to believe a crime was committed and whether there is probable cause to believe the person in front of the court is the one who committed the crime.
Rarely does a judge overturn the prosecution and dismiss the case. In fact, the prosecution or judge can add additional charges to the case at this hearing. Although the police officer may prosecute the preliminary hearing before the district justice, in Allegheny County an assistant district attorney will usually appear and present the case on behalf of the Commonwealth. If a prima facie case is presented, the case will be held for court. If a prima facie case is not presented, the defendant should be discharged.

Step #10: INFORMATION FILED
After holding a case for court, the district justice will send notice to the county clerk of courts who in turn will notify the district attorney. The district attorney’s office will then file a formal charging document, called an information, with the clerk of courts. The information will specify in particular counts the offenses charged against the defendant. At this stage, the district attorney may exercise discretion and terminate the prosecution by declining to file an information or by adding or deleting charges.

Step #11: FORMAL ARRAIGNMENT
The next proceeding is the formal arraignment, which may or may not occur before a judge of the court of common pleas. In Allegheny County, no judge is present. The defendant is provided with a copy of the information and advised of his rights, including his rights to file various pretrial pleadings. Generally, the district attorney is not represented at formal arraignment. All pretrial motions, including requests for a bill of particulars and discovery, and motions for continuance, severance or joinder, suppression, etc., should be filed within thirty days after the formal arraignment. It is the obligation of the district attorney’s office to respond to the defendant’s pretrial pleadings.

Step #12: PRETRIAL CONFERENCE
The next step is the pretrial conference. Generally, the defendant and his lawyer and an assistant district attorney will appear before the assigned judge and the course of disposition will be determined. All other pretrial matters should also be resolved at the pretrial conference. The defendant may elect to plead guilty, or to proceed to a jury or non-jury trial.

Step #13: TRIAL OR PLEA DISPOSITION
A defendant entering a plea of not guilty may choose to be tried by a jury of twelve citizens or by the judge alone. At trial, the case for the Commonwealth is presented by an assistant district attorney who must establish the defendant’s guilt beyond a reasonable doubt. The defendant is under no obligation to present evidence or testimony but may do so if he wishes. If tried by a jury, the jury must return a unanimous verdict; if tried non-jury, the judge must return the verdict. If a defendant is found not guilty, he will be immediately discharged. If found guilty, the defendant may be sentenced immediately or sentencing may be deferred pending a pre-sentence investigation into the defendant’s background. If sentencing is deferred, the defendant is subsequently returned to court and sentenced; at any sentencing hearing, an assistant district attorney will appear and present the Commonwealth’s position.

Step #14: JURY SELECTION
Residents of Allegheny County are randomly selected from state drivers’ license records, voter registration rolls, and are summoned on a daily basis to the Courthouse as potential jurors. A blind draw selects a pool of people from that group; the Judge, Prosecutor and defense attorney voir dire, or question, the jurors about their backgrounds and beliefs. The attorneys are permitted a limited number of "peremptory" challenges to various jurors and an unlimited number of challenges for good cause, the number of peremptory challenges depends on whether the defendant is charged with a misdemeanor, felony or homicide.
After twelve acceptable jurors are selected, the Judge administers an oath to the jury and reads basic instructions about the trial process, etc.

Step #15: JURY TRIAL
A jury trial is the fact finding phase of the case. It is the in-court examination and resolution of a criminal case. At the trial a decision will be reached as to the innocence or guilt of the defendant. Unlike a plea-bargained settlement which completes the case prior to trial, a trial introduces risk for both the prosecution and defense. Neither side knows which side will win. The trial begins with the prosecution's opening statement. The defense attorney may also present an opening statement at this time. The prosecution presents his case to support the charges and then rests. The defense presents his case to refute the charges and then rests. Closing arguments by both the prosecution and defense conclude the presentation part of the trial. The jury then deliberates innocence and guilt.

Step #16: NON-JURY TRIAL
In a Non-Jury trial it is the Judge that decides the case instead of a 12 panel jury.

Step #17: GUILTY PLEA
A defendant may choose to waive his right to a trial and enter a plea of guilty, which admits his guilt of the crimes charged. If a defendant elects to plead guilty, a plea date will be scheduled, at which time it will be determined that the defendant is knowingly and voluntarily entering a plea of guilty to the charges against him. An assistant district attorney will appear at the guilty plea hearing and represent the Commonwealth. Once the judge accepts the plea, the defendant may be sentenced immediately or sentencing may be deferred pending a pre-sentence investigation into the defendant’s background. If sentencing is deferred, the defendant is subsequently returned to court and sentenced; at any sentencing hearing, an assistant district attorney will appear and present the Commonwealth’s position.

Step #18: PRE-SENTENCE INVESTIGATION AND REPORT
The court’s probation department prepares a report for the judge summarizing the crime, and the defendant’s personal and criminal backgrounds. Generally, the victim is contacted for a statement.

Step #19: SENTENCING
Sentencing in Pennsylvania varies with the crime and can be the most confusing part of the criminal process. Most often, sentences are at the judge’s discretion; however, in Pennsylvania there are a number of mandatory minimum sentences that must be imposed if a defendant is convicted of a specified crime. At the time of sentencing, the judge will consider the information in the pre-sentence report before determining the sentence. The parties may correct factual errors in the pre-sentence report and offer additional evidence relevant to the judge’s sentencing decision. The judge will also consult the "sentencing guidelines" (established by the Pennsylvania Commission on Sentencing as a reference for framing an appropriate sentence throughout the state, considering factors of the crime and the defendant’s criminal background) to determine the minimum jail/prison sentence. The judge may consider different alternatives, such as a fine, probation, community service, a sentence to jail or prison, or a combination. The judge must also order the defendant to make restitution to any victims who have suffered financial harm.

Step #20: APPEAL
Once sentenced, the defendant has a choice of seeking review in the trial court or through an appeal to an intermediate appellate court, called the Superior Court of Pennsylvania. If review is first sought in the trial court and denied, the defendant may then appeal to the Superior Court. If the defendant’s appeal to the Superior Court is unsuccessful, the defendant has a discretionary appeal to the Supreme Court of Pennsylvania. The district attorney’s office will answer the defendant’s appeal by filing the appropriate responsive pleading.

There are three kinds of appeals: (1) interlocutory, (2) of right, and (3) by leave.

Interlocutory appeal: occurs when a party tries to appeal a judge's decision before the case has come to trial or before a trial is finished.
Appeal of right: occurs after a final order has been entered by the trial court (either a sentencing order, or an order dismissing the charge. Most appeals of right now focus on the sentence imposed.
Discretionary Appeal(or appeal by leave of the court): occurs when an appeal of right is not available (e.g., because an available appeal of right was not filed on time). The appellate court has the discretion to reject the appeal or can "grant leave". Except for capital (death penalty) appeals, all appeals to the Supreme Court of Pennsylvania are by leave of court (called allocatur).
The defendant and Prosecutor file briefs that summarize the case facts, frame the legal issues to be decided, and present persuasive written arguments (supported by constitutional, statutory or prior case decision authority). After the briefs are filed the case is scheduled before the appellate court judges for oral argument. The appellate court will eventually issue a written opinion (or several opinions, if the justices disagree). Not all appellate opinions are "published" (i.e., printed in official "reporter" services, such as the Pennsylvania Reporter). The legal analysis and conclusions in published opinions are given greater precedential authority than "unpublished" opinions.

Step #21: POST-CONVICTION RELIEF
Defendants also have a limited right to a collateral review of their conviction through the Post Conviction Relief Act. This action commences in the court of common pleas and review can thereafter be sought in the state appellate courts. Defendants may also seek federal review of their state convictions by filing a writ of habeas corpus in the appropriate federal district court. The district attorney’s office will file answers to these collateral petitions where appropriate.

Within this system, the primary obligation of the district attorney is the presentation of charges in the information and the prosecution of the case in the court of common pleas. To perform these critical tasks a division of labor has been created within the district attorney’s office. Initially, when notice is received from the clerk of courts that a case has been held for court, the case will be received by the Pre-trial Screening Unit. Lawyers in this department review the case and determine what charges will be placed in the information. After a case has been screened, and the information filed, it will be assigned to a trial unit based upon the nature of the case. In this office there is the General Trial Unit, which handles most misdemeanor and minor felony cases, and several specialty units: Homicide, Crimes Persons, Robbery/Theft and Narcotics. Assistant district attorneys within each unit then handle cases. There is also a Post-trial Unit which handles both direct and collateral appeals filed by defendants; this unit also litigates appeals initiated by the district attorney’s office when required.

The district attorney’s office has also established separate departments for such tasks as initiating independent investigations, administering pre-trial and trial diversionary programs, prosecuting juvenile cases and for asset forfeiture.