Orin Kerr (TVC) has an interesting analogy that provides a unique perspective on the DMCA

First, he fairly summarizes the fair use argument:

...the DMCA is unconstitutional because it violates the right to fair use guaranteed by the First Amendment. As I understand it, the argument generally goes like this: 1) copyright law allows a fair use defense; 2) the Supreme Court has suggested that copyright's fair use defense may be required by the First Amendment; 3) the DMCA prohibits people from circumventing access controls to a copyrighted work even if the infringement that would occur would be a fair use; and 4) by prohibiting conduct that would be fair use, the DMCA violates the First Amendment.

He then compares it to the insanity defense in criminal law i.e. an affirmative defense which when unraveled provides an argument as to why the First Amendment doesn't invalidate the DMCA:

the First Amendment requires a fair use defense to copyright infringement. As I see it, this does not necessarily mean that the First Amendment invalidates any other law (such as the DMCA) that prohibits acts that would constitute (or at least lead to) protected fair use. Again, this doesn't mean that the DMCA is a good thing from the standpoint of public policy. But I think it does point to a weakness in one of the occasional constitutional arguments raised against it.

[Orin Kerr, The DMCA and the right to fair use]

Professor Jack Balkin responds.