Not all copywriters are advertising copywriters. This in itself causes some confusion as the latter is the more famous (especially after the phenomenon that was Mad Men).
Medical copywriters have their own special niche, which I don’t pretend to know about or comment on here.
Copywriting has nothing to do with copyright law.
Ironically, one of the big problems in communicating what copywriters do is a lack of clarity around the definition of the word itself. Turns out, like a doctor that smokes, copywriters aren’t very good at communicating the nuances of their role.
Jesse Forrest, for example, distinguishes between copywriters, who write to get people to take an action, and content writers, who write to inform. But who ever heard of a content writer? Here at Articulate we do both of those things, so are we just plain writers?
No. Because the minute you say ‘I’m a writer’ people think novels, poems and maybe journalism. It’s a linguistic minefield.
Personally, I rather like Iain Broome’s answer:
To be a copywriter is beyond definition, but it’s fair to say that one thing binds us together: we all work with words on a daily basis.