Copyright can be a confusing and daunting subject. I've looked into it many times and I always eventually seem to forget the important parts. I'm hoping someone could answer me this:
When is it appropriate to use the TM symbol in your logo? If I remember correctly, a Registered Trademark is the (R) symbol? And TM is something you can put on any logo you create, registered or not, providing you are planning to use it commercially? This this right?
The TM symbol is an unregistered trademark, but I don't think it's exclusively for commercial products, I think you could use it for freeware goods too. If it did ever come to legal bother though, you'd have to prove that your original logo could be deemed identifiable and unique i.e., if someone copied your logo, you'd have to prove that you didn't copy it in the first place - or at least that's my understanding of it.
The (R) symbol is a definite no-no unless you actually register your logo with the authorities.
It's more the fact that your original logo has to be just that - an original, and not just deviation of some other logo or symbol in current use.
As a for-instance, say if you made a logo that was just a red circle with LIAM written in it, you couldn't just go around suing anyone who used a red circle in their logo because it isn't justifiably unique - however, if they were using a red circle with IAM written in it with the same font, you'd have a decent case then. But even then you'd have to prove that they were damaging your interest somehow, it's not enough to simply say "this person is copying me", you'd have to say "this person has a logo just like mine, the person is doing this knowingly, and it's damaging my business by X, Y and Z". Whereas registered trademarks wouldn't be able to be legally copied at all, unregistered ones are much easier to copy, just as long as someone isn't passing off one product as another.
Again, that's my understanding of it, maybe someone who's done copyright law could further inform us.