You can find an excellent explanation of the three theories (and
others) on this page:
First Amendment Principles and Approaches: Part II
Based on my own knowledge as someone with a B.A. in political science
as well as the above document, here is what the three positions are:
Absolute free speech: Just what the name implies. Free speech is an
absolute right, not merely the most important right. When the U.S.
Constitution says that Congress shall enact "no law" against free
speech, that means "no law." Under this theory, anything goes:
pornography, slander, libel, invasion of privacy, incitement to commit
crime, talking to members of a jury during a break in a trial, and so
Balanced free speech: In this approach, the desirability of free
speech is judged against other needs of society. Under this approach,
it might be OK to outlaw pornography, for example, because doing so
upholds morality and prevents exploitation. It might be also be OK
under this theory to make it illegal to criticize the President at a
time of war because it would embolden our enemies. With this
approach, free speech is far from absolute, and it is no more or less
important than other values.
Preferred position: This is the position that is most often used to
decide court cases in the United States. Free speech is seen as an
important, even vital, right but not the only right. Where there are
other rights involved, it is presumed that free speech will rule
unless curtailing free speech is the only way to prevent some sort of
grievous harm or abridgment of other rights. Under this kind of
reasoning, as an example, it makes more sense to lock up jurors during
a trial than to prevent public commentary on the trial. Or we would
allow almost any type of political speech as long as that speech
doesn't directly urge commission of a crime.
In my opinion, the preferred view makes the most sense. The absolutist
position leads to absurd results, and the "balanced" view means there
really isn't much free speech at all. The "preferred" view rightfully
recognizes that free speech is essential to having a free society.
Here are some other pages with information relevant to your question.
Links go to a wealth of comments on what freedom of speech (and other
First Amendment provisions) means.
Freedom of Expression Topics
Many essays on the topic.
Door No. 1: Muskets? Or Door No. 2: Free Speech?
A case study on one approach to the issue.
I hope you have found this useful.
Google search term used: "free speech" "preferred position"