Why didnt the federal gov do something about Jim crow laws?

The federal government was slow to intervene against Jim Crow laws due to a combination of factors, including widespread societal acceptance of racial segregation, the dominance of Southern political power, and the Supreme Court's rulings that upheld segregation as constitutional (e.g., Plessy v. Ferguson). Additionally, many federal officials were reluctant to confront the deeply entrenched racial attitudes of the time or risk political backlash. It wasn't until the Civil Rights Movement gained momentum in the 1950s and 1960s that significant federal action, such as the Civil Rights Act of 1964 and the Voting Rights Act of 1965, began to dismantle these discriminatory laws.