What is meant by "standards of justice have not always been met"? Provide examples of some efforts that have been made to reach the goals of justice at all?

For the answer to the question above,

Our nation was built on the concept of equal justice for everyone. However, blacks were enslaved and later faced discrimination, lynching, and unfair treatments. Other minorities have also been unfairly punished. The Civil Rights Act was one example of trying to reach goals of justice.