When a judge sentences a violent criminal to twenty years in prison, citizens believe that society will be protected from that individual for the next two decades. In reality, however, it is far more likely that the perpetrator will only be detained for about eight years. That routine discrepancy can be called the sentencing illusion.
Politicians and prosecutors frequently stand before cameras to announce lengthy prison terms in order to encourage citizens to conclude that justice has been served and dangerous criminals have been removed from society for the duration of their declared sentence.
The reason for this delusion is self-serving for all involved. The pronouncement caters to political perceptions. The reality is a product of incentives.
Prosecutors seek to be portrayed as relentless advocates for justice, and judges want to appear as impartial guardians of public policy. Yet each operates under a set of incentives that point in a different direction. As a result, crime victims, police officers, and ordinary citizens are often shocked and frustrated to find that reoffenders are back to their predatory ways after only serving a fraction of their stated sentence.
To understand why this deception has become normal operating procedure for our justice system, we must understand
