How have Congress and the courts justified placing limits on the freedom of speech?

Answer 1

http://www.freedomforum.org/packages/first/curricula/educationforfreedom/supportpages/l04-limitsfreedomspeech.htm

http://ever-increasing-entropy.blogspot.com/2009/12/legitimate-limitations-on-freedom-of.html

Answer 2

as always, just what i needed. thank you very much.

Answer 3

You're very welcome.