Whenever civil rights legislation is discussed, especially any threat to the existing civil rights legislation, there are always people read to defend the legislation by stating that without it this country could return to the "days of Jim Crow" because people would not be restrained from bigotry. It is a very spurious argument.
Yes, some people are bigots and would gladly indulge in their bigotry without the current civil rights legislation, but that does not equal a return to the "days of Jim Crow" because the most salient feature of Jim Crow is that it was law. It was passed by the various city, county, and state governments and enforced by the police. Those who violated Jim Crow laws were subject to legal sanctions.
It is important to remember, laws are passed to either to prevent someone from doing what they are already doing, or to compel someone to do what they are not doing. That statement is without value judgment, it is fact. But that implies that there were people willingly not complying with any racist culture that gave rise to the passing of the Jim Crow laws.
Some will object at this point by pointing out that the fact that the laws passed is proof of the racist culture and that the people would not have served minorities anyway. Even if the majority of the culture was racist, that does not mean all were. Laws are passed to stop people from doing what they are doing, even if that means ignoring any racist culture surrounding those allegedly minority businesses that operated without regards to race.
Also, assuming the dominant culture is an example of the Democratic Fallacy, that the actions of a government in a representative voting system automatically represent the will of the people who vote. It happens many times that there is a severe disconnect between the electorate and the elected, with countless examples available.
Still, there are those who will never be satisfied with knowing that Jim Crow was law, and try to insist that it was culture until another law superseded it. If it was cultural, then there exist the problem of explaining away the Montgomery Bus Strike, in which a majority of the people were in favor of a peaceful resolution of the strike. The strike only went on as long as it did because the government found ways to fight against its own people, the people that it allegedly represents and follows the will of.
The problem with civil rights legislation is that it is most often the case of one law combating another law. It is a case of conflicting levels of government passing laws to combat what the other levels of government are mandating or forbidding. That makes a poor case for arguing the necessity of new legislation, when the real case is repealing the old legislation that is creating the problem in the first place.