From the DC Health website

Medical Marijuana and Patients

Qualifying patients in the District have the right to obtain and use marijuana for medical purposes when his or her primary healthcare practitioner has provided a written recommendation that bears his or her signature and license number. This recommendation must assert that the use of marijuana is medically necessary for the patient for the treatment of a qualifying medical condition or to mitigate the side effects of a qualifying medical treatment. See the requirements and instructions for obtaining an identification card in the links below.

• Patient Application Package

• Minor Patient Application Package 

• Registration Card Replacement Form

• Frequently Asked Questions (FAQs)