Thoreau explains that the conscience need for Civil Disobedience 

 by pointing out that any person should fight and sacrifice for 

 what he or he believes is bias or unfair. And every conscience is 

 a driving force of anyone to fight and change everything that is 

 unfair in order to create a better,acceptable justice. He used the      principle to justify his claim by mentioning the example of ending    slavery ; he wanted to be justified only if the government is unjust and oppose the peoples' conscience.