An increasing number of US states have legalised cannabis in recent years, despite it remaining illegal under federal law. What is the future for this nascent industry?

An increasing number of US states have legalised cannabis in recent years, despite it remaining illegal under federal law. Gianna Palmer reports from a cannabis business expo in New York to gauge the enthusiasm of investors in this nascent industry, and Edwin Lane reports from Seattle on how Washington state's cannabis shops and growers are faring, four years after legalisation there. Sam Kamin, professor of marijuana law and policy at the University of Denver, explains why the complicated legal picture is so far putting off major businesses.

(Photo: James Lathrop, owner of Cannabis City in Seattle, Washington. Credit: BBC)