Here are some of the relevant statutes:
§ 7-2502.12. Definition of self-defense spray.
For the purposes of §§ 7-2502.12 through 7-2502.14, the term:
“Self-defense spray” means a mixture of a lacrimator including chloroacetophenone, alphacloracetophenone, phenylchloromethylketone, orthochlorobenazalm-alononitrile or oleoresin capsicum.
§ 7-2502.13. Possession of self-defense sprays.
(a) Notwithstanding the provisions of § 7-2501.01(7)(C), a person 18 years of age or older may possess and use a self-defense spray in the exercise of reasonable force in defense of the person or the person's property only if it is propelled from an aerosol container, labeled with or accompanied by clearly written instructions as to its use, and dated to indicate its anticipated useful life.
(b) No person shall possess a self-defense spray which is of a type other than that specified in §§ 7-2502.12 to 7-2502.14.
§ 7-2501.01. Definitions.
As used in this unit the term:
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(7) “Destructive device” means:
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(C) Any device containing tear gas or a chemically similar lacrimator or sternutator by whatever name known;
§ 7-2502.14. Registration of self-defense sprays.
(a) A person 18 years of age or older must register the self-defense spray at the time of purchase by completing a standard registration form.
(b) The vendor must forward the registration form to the Metropolitan Police Department.
All of the above is about as clear as mud. As a layman, I read it to tell me that:
1) under D.C. Code 7-2503.13, I can only possess pepper spray that contains a mixture of lacrimator including chloroacetophenone, alphacloracetophenone, phenylchloromethylketone, orthochlorobenazalm-alononitrile or oleoresin capsicum;
2) under D.C. Code 7-2501.01(7)(C), I cannot possess a spray containing tear gas or similar substances;
3) under D.C. Code 7-2502.13(a), which regulates the possession of "self-defense spray," I can only possess "self-defense spray" if I am over 18 years of age and I register the self-defense spray at the time of purchase by completing a standard registration form [available by calling (202) 727-4275 (Ref: http://mpdc.dc.gov/mpdc/cwp/view,a,1237,q,568998.asp)]; and
4) under D.C. Code 7-2502.13(b), my vendor must forward the registration form to the Metro PD if I am to be allowed to possess the self-defense spray in DC.
I'm unclear how anyone comes the conclusion that it is lawful to carry pepper spray purchased outside of the District in the District. To me, the law clearly states that any pepper spray possessed in the District must be registered with the Metro PD. Is there case law which constrains the application of the above only to pepper spray purchased in DC?