The famous Lemon slave case...

This was the famous case popularly known as the Lemmon Slave Case, a freedom suit initiated in 1852 by a petition for a writ of habeas corpus. The petition was granted by the Superior Court in New York City, a decision upheld by the New York Court of Appeals, New York's highest court, in 1860 on the eve of the Civil War.

The decision mandated the release of eight slaves, including six children, brought into New York by their Virginia slave owners, Jonathan and Juliet Lemmon, who were in transit while relocating to Texas. New York had abolished slavery gradually beginning in 1799, freeing all remaining slaves on July 4, 1827. An 1841 state law explicitly prohibited slaveholders from bringing slaves in transit to the state, liberating any slaves so brought.
There is much on the internet concerning the Lemmon Slave Case.