What did Black Codes prevent African Americans from?

Explanation:

While the codes granted certain freedoms to African Americans—including the right to buy and own property, marry, make contracts and testify in court (only in cases involving people of their own race)—their primary purpose was to restrict Black peoples’ labor and activity

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.