Here's a question for someone with more legal expertise than me that I've been wondering about:
How do intellectual property rights intersect with free speech rights?
I ask this because I know numerous examples of things like DVD commentaries and interviews that have had to be edited, or are otherwise prohibited from distribution in certain countries, solely because the person talking made a reference to a copyrighted or trademarked product. How does that work? What about going on stage in front of an audience and singing a copyrighted song? How does having legal repercussions for that behavior not end up a violation of free speech? Why can we only write works of fiction involving people living in a generic, brand-name-less world containing no recognizable commercial cultural references without having to pay someone for the right to even mention them?
I think people have a right to their works, but going so far as to allow private entities to impose punishments on people for the manner they choose to express themselves seems downright unconstitutional.
That's a very complex question, and one which would take me far too long to answer (and I'm too fucking lazy to look through my casebooks and shit right now). Suffice it to say that these types of issues generally fall under the umbrella of
fair use, which, at least in the USA, is somewhat different for copyrights and trademarks, which are two very different types of legal protections.
Public performances and uses of songs, audio recordings, etc. generally require the permission of the copyright holder, unless such performance falls into one of the fair use categories. I'm reminded of the time that Sarah Palin got threatened with legal action for using Heart's song "Barracuda" in her campaign.
I hope that is an adequate but concise answer. I really can't comment on what the laws are outside the USA, but I imagine that at least in the Anglophone world, there would be some similarities.