In parallel to the instant abolition, the concept of gradual emancipation was developed in New England by the end of the 1770s and was codified in laws of several US states in 1780–1804.
The law stated that those born to slave mothers after January 31, 1813 would be granted freedom when contracting matrimony, or on their 16th birthday for women and 20th for men.
[4] In Peru, the president José de San Martín established "the freedom of wombs" for those born after the declaration of independence in 1821.
As a compromise, Parliament enacted a law freeing children born to enslaved women.
Similar gradual abolition laws had been passed in some of the northern United States after the American Revolutionary War, namely, New York in 1799 and New Jersey in 1804.