In which Supreme Court case did this provision of the Northwest ordinance play in important part

It seems there might be a missing reference to a specific provision of the Northwest Ordinance in your question. However, I can provide information on a significant Supreme Court case related to the Northwest Ordinance and its provisions.

One crucial provision of the Northwest Ordinance of 1787 was the prohibition of slavery in the Northwest Territory (the area that would become the states of Ohio, Indiana, Illinois, Michigan, and Wisconsin). This anti-slavery provision played a role in the Supreme Court case of Dred Scott v. Sandford (1857).

In the Dred Scott case, Dred Scott, a slave, had lived with his owner in a free territory and a free state. He argued that residing in these places should make him a free man. The Supreme Court, however, ruled against Scott, stating that African Americans, whether enslaved or free, were not considered citizens and therefore had no standing to sue in federal court. Additionally, the Court declared that Congress lacked the authority to prohibit slavery in the territories, directly challenging the anti-slavery provision of the Northwest Ordinance.