Slowly but surely, marijuana prohibition is ending. Legalization can help undo the racist impact of the war on this widely used drug - but it could also help perpetuate injustice.

Four states and the District of Columbia have passed measures to legalize marijuana for adult recreational use, and many more allow use for medical purposes. Those numbers will almost certainly grow this year, with my home state of California likely leading the way.

But state governments, as well as the burgeoning legal marijuana industry, need to get this right.

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