“Un-American activity cannot be prevented or routed out by employing un-American methods; to preserve freedom we must use the tools that freedom provides.”

Thinking About a White Future, 1998
1990s, 1990

As quoted by Terry Dorian, Total Health and Restoration: A 180-Day Journey (2002), p. 49. Other versions include:
[The] Constitution of this republic should make special provisions for medical freedom as well as religious freedom ... To restrict the art of healing to one class of men and deny equal privilege to another will constitute the Bastille of medical science. All such laws are un-American and despotic. They are fragments of monarchy and have no place in a republic. [in Robert L. Schwartz, "Laetrile: The Battle Moves into the Courtroom," American Bar Association Journal, February 1979, p. 226, no citation given]
Unless we put medical freedom into the constitution the time will come when medicine will organize into an undercover dictatorship and force people who wish doctors and treatment of their own choice to submit to only what the dictating outfit offers.
Laws restricting the practice of the healing art to one class of physicians and denying equal privileges to others, constitutes the Bastilles of Medicine, for they prevent progress. They are relics of Monarchy, and therefore have no place in a Republic. [in Thomas Morgan, "National Board of Health. The Other Side of the Question, As It Appears to Thomas Morgan," Youngstown Vindicator, 27 January 1911, p. 6]
This quote is often cited with regards to Rush, and can rarely be found attributed to his autobiography, but does not exist in that book http://books.google.com/books?id=EkTM9Kn9F4IC&q=%22into+the+constitution%22#v=onepage&q=%22into%20the%20constitution%22&f=false http://hpy.sagepub.com/content/16/1/89.abstract. The quote contains words and phrasing that seem anachronistic to late 18th century America.
Misattributed

"The One Un-American Act," Speech to the Author's Guild Council in New York, on receiving the 1951 Lauterbach Award (December 3, 1952) http://ala.org/ala/aboutala/offices/oif/foryoungpeople/theoneunamerican/oneunamerican.cfm
Other speeches and writings

Television interview on MTV's Enough is Enough (19 April 1994) http://www.presidency.ucsb.edu/ws/index.php?pid=49995
1990s
Context: When we got organized as a country and we wrote a fairly radical Constitution with a radical Bill of Rights, giving a radical amount of individual freedom to Americans, it was assumed that the Americans who had that freedom would use it responsibly. That is, when we set up this country, abuse of people by Government was a big problem. So if you read the Constitution, it's rooted in the desire to limit the ability of — Government's ability to mess with you, because that was a huge problem. It can still be a huge problem. But it assumed that people would basically be raised in coherent families, in coherent communities, and they would work for the common good, as well as for the individual welfare.

Source: American Constitutional Law (1978), Approaches to Constituitonal Analysis

"Indoors and Out", Nature Magazine number 33 (May 1940) p. 255, quoted in Mark Harvey, Wilderness Forever (2005) p. 45

The American Mind: An Interpretation of American Thought and Character Since the 1880s (1950)
Context: With the Sedition and Espionage Acts … the "red hysteria" of the Twenties, the Alien Registration Act of 1940, the loyalty tests and purges of the mid-Forties, the establishment of un-American Activities Committees, intolerance received, as it were, the stamp of official approval. Loyalty was identified with conformity, and the American genius, which had been experimental and even rebellious, was required to conform to a pattern.

CNN "Rock the Vote", Nov 5, 2003

The secret memorandum Reflections on the Treatment of Peoples of Alien Races in the East (25 May 1940)
1940s