Nike has long relied on controversy in marketing an image of edgy youthfulness. The company had Charles Barkley declare that he is not a role model and Tiger Woods remind people that some country clubs would turn him away because of his skin color. It dressed the tennis player Andre Agassi in jean shorts.
This week Nike returned to that tradition, revealing Colin Kaepernick, the polarizing former N.F.L. quarterback, as a face of a major new marketing campaign, the 30th anniversary of its iconic “Just Do It” slogan, a move that may prove to be its most controversial yet.