Determined to go over johnson’s head and fix the wrongs the black codes brought about; congress learned how to use its greatest tool, its right

The correct answer is its right to make laws/amendments.

For example, Congress passed multiple amendments during Reconstruction to help newly freed slaves obtain their constitutional rights.

The 14th amendment (1868) ensured that all people born on US soil were given citizenship. Along with this, the 14th amendment includes the equal protection clause. This means that the freedoms and liberties given in the Constitution must be protected equally for all citizens.

The 15th amendment (1870) gave all African-American men the right to vote in elections.

From mexican american war , us gained new mexico.