DATA Story: Inside the Incident-Arrest-Charge Funnel

Philadelphia DAO
Oct 31, 2019 · 4 min read

A glimpse into the basic mechanics of the criminal justice system

Although there are several ways that a criminal case can be charged in Philadelphia, the most common path involves three steps:

  1. Incident: An incident of suspected criminal activity is reported to the police. An incident can be reported through a call to 911, directly to a police officer, or by an officer directly observing criminal activity. When the police receive an incident report, they investigate the incident and try to determine if there is a suspect to arrest. In some situations, such as when the police directly observe the criminal activity, they can make an arrest immediately. In others, an investigation can take days or months. In many cases, the police never make an arrest or determine that no criminal activity has taken place.

It is important to understand that the Incident-Arrest-Charge cycle is a giant funnel: There are far more incidents reported to the police than there are arrests made. Because the District Attorney’s office may decline to charge some arrests based on a variety of factors such as not having enough evidence or for other policy reasons, there are generally more arrests made than cases charged and prosecuted.

The chart below shows all reported Part I and II incidents (this is what the police reports out, although it excludes many common offenses like Simple Assault) as compared to all arrests and cases charged (for all offense types) since 2014. Even when compared to only a subset of incidents, there are 3–4 times as many incidents reported as there are arrests and charges. On the other hand, cases charged and arrests closely track each other.

Although it is generally true that for any given offense type there are many incidents, but fewer arrests and even fewer charges, that narrative isn’t universally true. Drug cases, as shown in the chart below, are often developed directly from police investigation and observation. The police may watch a known drug corner, wait for multiple sales to occur, and then arrest multiple buyers and sellers simultaneously. That means that a single “incident,” as reported in the data, leads to multiple arrests and cases charged.

Finally, there are also offense types where there are more charges than arrests. The graph below shows incidents, arrests, and charges for robbery with a gun. Unlike the previous two graphs, there are more cases charged in every time period. This is because when a person is suspected of committing a robbery with a weapon, there are frequently multiple cases to charge against that individual. For example, the person may be charged with robbery in one case and aggravated assault in another case. If multiple people were robbed, each victim would generate a new case against the individual suspected of committing the offense.

If you are interested in learning more about the incident-arrest-charge funnel, please look at our reports on incidents, arrests, and charges.

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