Why did the protection of civil liberties gain importance in the 1920s?

This was the progressive era in which people started fighting for their civil rights because the government was becoming more and more powerful and started regulating everything which often infringed upon the civil rights of the people. For example, there was the espionage act which stated that anyone criticizing the government could be treated as a foreign spy and put on trial which heavily limits free speech as the fundamental pillar of civil liberties.

Independent executive agencies are more specialised.