Proportional justice is a concept of fairness and reasonableness.  In criminal law, it means that the consequences imposed for criminal behavior should be tailored to the severity of the crime.

Minor offenses should be met with minimal consequences, while major offenses involving extreme violence should be met with severe consequences.

When determining a fair,  just, and proportional sentence, each case and each offender must be judged individually.  

The process of reaching proportionality should include not only the facts and circumstances of the crime and the offenders particularized role in the crime but also must include a consideration of his criminal history, social history, age, intoxication, mental illness, duress, coercion, peer pressure and any other factor that aggravates or mitigates culpability for the offense.  

Blanket, one-size-fits-all policies are lazy and often lead to disproportional consequences that can be either too harsh or too lenient on a particular offender.

Simply put, the punishment must fit the crime and the offender.