Primary Submission Category: Instrumental Variables
Impact of Prosecutorial Systems on Charging Decisions: Application of the Instrumental Variable Method
Authors: Takuma Iwasaki,
Presenting Author: Takuma Iwasaki*
In the field of criminal law and policy, there has been limited research applying causal inference methods, because most new laws and systems apply to all entities uniformly and simultaneously in order to maintain equality, which makes it challenging to establish a control group. Focusing on a case where two comparable systems coexist, my research shows the impact of organizational systems on prosecutors’ charging rates.
In most countries, prosecutors’ offices are organized using one of two systems. In the first system, the same prosecutor handles cases all the way from investigation to trial. In the second system, different prosecutors are responsible for investigation and trial, respectively, where one prosecutor decides to charge, but does not have to spend its time on the subsequent trial.
Interestingly, both systems coexist in Japan, but there are unobserved confounders, such as severity of criminal cases in each area, affecting both the system selection and charging rates. However, the system selection primarily hinges on geographical proximity to major prosecutor’s offices, making the proximity an instrument, since it does not directly impact charge rates, and is unrelated to the unobserved confounders.
My research reveals that the second system increases charge rates by 15.6% [95% CI: 2.4 – 28.8%], suggesting that prosecutors in the second system charge more aggressively since they do not have to “pay the price” for it.