The Problems with Pepper Spray
Briefly, the article talks of the issues taking a law enforcement tool and using it in the civilian world. Credit goes to Modern Combatives Systems Blog.
Also, if you choose to use/carry the spray, learn to do so properly. Much like when striking someone, you need to be moving away from where you were (stay on the X and he will likely strike out at the location).
You can find more personal defense items at MW Security Systems