Official Declaration 2

 Having served a mission during the time that blacks could not hold the priesthood, I reference the  preface comments to this declaration - 

"...During Joseph Smith’s lifetime, a few black male members of the Church were ordained to the priesthood. Early in its history, Church leaders stopped conferring the priesthood on black males of African descent. Church records offer no clear insights into the origins of this practice. Church leaders believed that a revelation from God was needed to alter this practice and prayerfully sought guidance."  (Doctrine and Covenants, OD 2, Heading)

Thus the declaration came by revelation.

I specifically note that there is a difference between doctrine and policy.