Whether you're living in Washington DC or just passing through, you may want to know whether cannabis is legal there. The truth is a bit complicated because even though you may have seen ads for cannabis delivery services, that's a bit misleading. You cannot buy or sell cannabis in Washington DC.
Initiative 71 was a voter-approved ballot initiative that was passed in November of 2014. It made cannabis possession legal for anyone over the age of 21 to possess up to 2 ounces or less of cannabis. It also made it legal to use on private property. It also made it legal to transfer up to one ounce or less of cannabis to another person 21 or older on the condition that no money, goods, or services are exchanged.
Initiative 71 did not legalize cannabis sales for recreational use. Only medical dispensaries exist in Washington DC.
An article on how to buy weed in DC exists on UrbanAroma. It explains how the law works and clarifies ways to acquire cannabis legally within the District of Columbia. One such method is cannabis delivery. When you order delivery, you're not paying for the cannabis, you're paying for the delivery of a separate item and the cannabis is considered to be a gift.