The first time in recorded human history that slavery was eradicated by legislative power of government was:

Correct Answer is: In the USA in 1777 after the revolutionary War

Explanation:

The United States is a very important country in the History of the Abolition of Sclabitude, After the Revolutionary War between the British and their 13 Colonies the first attempts to end Slavery were made. In 1777 the newly founded Vermont established in a constitution that "It is absolutely necessary, for the welfare and safety of the inhabitants of this State, that it should be, henceforth, a free and independent State...", This is the first time in history that the slavery was eradicated by the legislative power.

This influenced other laws gradually prohibiting slavery, such as in 1794 and 1800 where it was stated that no Slavery trades could be made by the Americas, the abolitionist movement started to grow mostly in northern states and by 1804 all of the northern states were free of slavery. Even after this other forms of slavery remained in the country, like the Indentured servitude, and was not until 1948 with the Universal Declaration of Human Rights that these other forms of slavery where eradicated.

regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.