Using pepper spray is good in self defense but you need to remember that local regulations may restrict you from using it. Therefore, you need to know about the regulations of the area wherever you are going to use it. The best way is to ask the local police to learn of the local regulations.
One of the instances where you are precluded from even carrying one with you is when you travel by air. No airline allows you to carry this non lethal self defense spray with you. Also there are certain cities states and countries where the use of it is not allowed.
Though it is an innocent weapon that does not create any long term effects on a victim, there is the possibility of people misusing it. That is why many cities states and countries do not allow using or even carrying it with you. Therefore, always educate yourself on rules and regulations before buying and using it.