This narrative, reinforced over decades of marijuana prohibition, is reflected in racial disparities in marijuana arrests. In 2010, black people were nearly four times as likely to be arrested on charges of marijuana possession as whites, even though they use the drug at about the same rate.

Legalization has barely made a dent in those disparities. As of 2014 in Colorado, the marijuana arrest rate for black people was almost three times that of whites. In New York City, the marijuana arrest rate for black people in New York City was over four times that of whites; the Bronx has one of the country’s highest rates of marijuana arrests. Meanwhile, black people make up an estimated 1 percent of marijuana dispensary owners, owning less than three dozen of the 3,000 or so retail shops nationwide.

Too many people have been deported, made homeless, lost financial aid, levied fines and fees or had their children taken away from them because of marijuana arrests.

White entrepreneurs who are cashing in on legal marijuana must work to reverse these trends. People in the marijuana industry, and the lawmakers who help it flourish, should highlight the racist history of marijuana prohibition and acknowledge its continuing impact.

The cannabis industry must also press for policies to decriminalize marijuana. It should call for the release of people like Mr. Winslow who sit in jails and prisons for the mere use, possession or sale of marijuana. And it must push legislators, prosecutors and law enforcement officers to throw out convictions derived from marijuana offenses.

Cannabis profiteers and customers should also push their lawmakers to emulate Massachusetts, Pennsylvania, Florida and the city of Oakland, Calif., each of which has enacted policies, in some cases described as “marijuana reparations,” that encourage and give priority on retail licenses to people of color and those who have been disproportionately harmed by marijuana prohibition and enforcement.