I Wish I Was Making This Up
From the Boston Police Department website's FAQ page "How to Apply for a Restricted Firearms Identification Card for Mace/Pepper Spray Only" comes this brilliant exchange:
Now you know.
- Q: Why is a Restricted Firearms Identification Card for chemical spray needed?
A: Massachusetts General Law (MGL) Chapter 140 ยง 129B requires that a person be licensed in order to purchase, and/or possess chemical sprays. A violation of this statue is a criminal offense.
Now you know.