The Emergency Civil Liberties Committee (later The National Emergency Civil Liberties Committee) was started in 1951 in response to the McCarran Act or the “Subversive Activities Control Act of 1950.” The mission of the organization was to defend the rights of “free speech, religion, travel, and assembly.”  The McCarran Act was one of the driving forces behind the “Red Scare” of the 1950s and the rise of McCarthyism. The group was modeled as a more vigorous version of the American Civil Liberties Union and participated directly in the defense of those charged as communists and subversives under the McCarran Act. Throughout the 1950s the NECLC was accused of being a communist front organization because the group was founded and run by people like its chairman Corliss Lamont who were not members of the Communist Party USA but were known as fellow travelers.  Lamont was also previously the director of the ACLU.
The NECLC merged with the Center for Constitution Rights in 1998 but had previously taken cases involving the draft and anti-war protests, child welfare and immigration. They also represented James Peck, a Freedom Rider beaten by the KKK in 1961 who sued the FBI in 1976 for having knowledge of his attack and not acting. The NECLC was run by Edith Tiger from 1968 until 1998.
I have included a reprinting of the Bill of Rights and a few pages from one of their publications about the McCarran Act (and a cartoon that I do not understand at all).