What was the name of the proposed law that would ban slavery in all territory won in the mexican-american war?

The Wilmot Proviso

In 1846, Congressman David Wilmot, representant to the Democrats in the United States House of Representatives from Pennsylvania, proposed an attempt called the Wilmot Proviso. The Wilmot Proviso was intended to ban slavery within the land acquired as a result of the Mexican- American War 1846-48.

The Wilmot Proviso turned to be unsuccessful, the proposal in the United States Congress to ban slavery in territory acquired from Mexico in the Mexican–American was again in 1847 tried to carry on, but again failed. One of the main reasons was the vast majority of slavery support in the South.