Push for repeal of the Espionage Act of 1917's First-Amendment-violating provisions.

In 1917, Congress enacted the Espionage Act to allow a person who "willfully cause[d] or attempt[ed] to cause insubordination, disloyalty, mutiny, or refusal of duty in the military or naval forces of the United States, or shall willfully obstruct the recruiting or enlistments vice of the US" to be imprisoned, if the United States was at war at the time that person did so.
A clause in the act suggests that the act was not intended to restrict freedom of speech. However, the federal government used the Espionage Act to arrest people who spoke out against the war. It has not been repealed since then, not even by the Supreme Court. The Supreme Court, in 1917, upheld the law's constitutionality.
This part of the law is no longer enforced, but it still exists.