As a young man Martin Van Buren owned a few slaves, as had his father.
His only slave, Tom, ran away in 1814 (approx.) When Tom was found 8 years later, Van Buren offered him for sale to the finder for $50. (Cole,p110)
1821: A convention to create a new constitution for New York proposed forbidding free Blacks from voting (which they had been able to do in New York until then). Van Buren fought that but approved a compromise that allowed only Blacks who possessed $250 to vote. He said this “held out inducements to industry." (cole p13)
1837: "The last, perhaps the greatest, of the prominent sources of discord and disaster supposed to lurk in our political condition was the institution of domestic slavery. Our forefathers were deeply impressed with the delicacy of this subject, and they treated it with a forbearance so evidently wise that in spite of every sinister foreboding it never until the present period disturbed the tranquility of our common country. Such a result is sufficient evidence of the justice and the patriotism of their course; it is evidence not to be mistaken that an adherence to it can prevent all embarrassment from this as well as from every other anticipated cause of difficulty or danger. Have not recent events made it obvious to the slightest reflection that the least deviation from this spirit of forbearance is injurious to every interest, that of humanity included? [Before the election I declared that:] ‘I must go into the Presidential chair the inflexible and uncompromising opponent of every attempt on the part of Congress to abolish slavery in the District of Columbia against the wishes of the slaveholding States, and also with a determination equally decided to resist the slightest interference with it in the States where it exists.’" (Van Buren.)
1840: President Van Buren ordered a federal marshal to bring the Amistad prisoners to a Navy ship to be returned to their Spanish (alleged) owners. The courts ruled against Van Buren and, a year later, the prisoners went free. (Cole, p362)
1840: President Van Buren got in trouble with the South for supporting his Navy secretary’s decision that Black witnesses could testify in a court martial, even though the alleged crime took place in North Carolina which forbid such testimony. (Cole, p362)
1848: Van Buren was nominated for president by the Free Soil Party, and accepted a platform that called for keeping slavery out of the territories. Van Buren announced that, if elected, he would not veto a law that forbid slavery in the District of Columbia. (Cole, p415)