From what I have gathered and I'm no expert on the subject but Pepper Spray is legal in all 50 states, however a number of cities and states have restrictions on sizes, strengths, etc.. If you have a question, it is wise to check with your local city or state attorneys office or police department for specific laws about the possession and use of pepper spray products in your city or county. Defense sprays should only be purchased by those 18 years of age or older. This list may not be totally accurate or complete and ReptiTactical accepts no responsibility for its accuracy or completeness. As stated above it's always best to find out your states laws. 

We Cannot ship to these states. If an order is placed, your order will be canceled.
New York: New York residents may only purchase defense sprays from licensed Firearms Dealers or licensed Pharmacists in that state.
Massachusetts: It is illegal for pepper spray to be mailed to Massachusetts, but it may be lawfully carried by private citizens. Before it is legal for any resident of the state to purchase the spray, a dealer must obtain a proof of age 18 or over with a valid form of identification. However Individuals between the ages of 15 and 18 must still have a valid firearms identification (FID) card to purchase self-defense spray. These are very easy to get: you simply request one at any local police station, fill out the required form and provide two separate types of identification. Every FID has a processing fee of $2, and takes about a week to receive.

States Where Pepper Sprays Have Some Restrictions

California: "Penal Code Title 2: Control of Deadly Weapons Chapter 4: Tear Gas Weapons Article 1: General Provisions Section 12403.7
Notwithstanding any other law, any person may purchase, possess, or use tear gas and tear gas weapons for the projection or release of tear gas if the tear gas and tear gas weapons are used solely for self-defense purposes, subject to the following requirements:

(a) No person convicted of a felony or any crime involving an assault under the laws of the United States, the State of California, or any other state, government, or country or convicted of misuse of tear gas under subdivision (g) shall purchase, possess, or use tear gas or tear gas weapons.

(b) No person who is addicted to any narcotic drug shall purchase, possess, or use tear gas or tear gas weapons.

(c) No person shall sell or furnish any tear gas or tear gas weapon to a minor.

(d) No person who is a minor shall purchase, possess, or use tear gas or tear gas weapons. 

(e) (1) No person shall purchase, possess, or use any tear gas weapon that expels a projectile, or that expels the tear gas by any method other than an aerosol spray, or that contains more than 2.5 ounces net weight of aerosol spray

Michigan: Pepper spray must not be more than 10% and can be used for self defense. “The reasonable use of a self-defense spray or foam device containing not more than 10% oleoresin capsicum by a person in the protection of a person or property under circumstances that would justify the person’s use of physical force. The Canister size is restricted to 35grams approx. 1.2oz.
Wisconsin: Tear gas is not permissible. By regulation, OC products with a maximum OC concentration of 10% and weight range of oleoresin of capsicum and inert ingredients of 15-60 grams are authorized. This is 1/2 oz. and 2 oz. spray. Further, the product cannot be camouflaged, and must have a safety feature designed to prevent accidental discharge. The units may not have an effective range of over 20 feet and must have an effective range of six feet. In addition there are certain labeling and packaging requirements: must state cannot sell to anyone under 18 and the phone number of the manufacturer has to be on the label. The units must also be sold in sealed tamper-proof packages.
Washington DC: Pepper spray may be purchased in the state or online, but before a citizen/vistor may legally possess any type of safety spray they must first register the weapon at a local DC police station. Personally I would call ahead of time to register.  Registering allows law enforcement officers to know exactly who is carrying any type of defense spray and to help make sure they are used in a lawful manner. Only people who are 18 years or older may purchase and register a canister of spray on their own, but anyone 14 or older may do so as long as they have the permission of a parent or legal guardian.
States that do not have shipping restrictions on OC defense spray products:
Alabama, Arizona, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington State, West Virginia, Wyoming,