Just wondering where idea become expression. Let's take The Lord Of The Ring as an example, if i want to write a boook about two alchemist heading to a tower in order to destroy the ring of evil, would it be a rip of idea or expression?
FYI no, i'm not gonna write a book about it. :P You can answer me using Harry Potter as an example if you want, just interested in understanding where the line is.
Expression is tied up with fixation. Copyright subsists in a work that is fixed in a tangible medium of expression from which they can be reproduced, perceived, or communicated. 17 USC 102
This expression is protected, not the idea. However, copyright infringement can occur even when there is not an exact copy. First, courts use a substantial similarity standard to determine if infringement has occurred. Second, when a character or plot is sufficiently developed, taking that character or that plot can be infringement, even if not expressed in the exact same manner.
"We do not doubt that two plays may correspond in plot closely enough for infringement [...] the less developed the characters, the less they can be copyrighted; that is the penalty an author must bear for marking them too indistinctly." Nichols v. Universal Pictures Corporation, 45 F.2d 119 (2d Cir. 1930)
Some characters or plot elements are so common to a genre that they are either not considered "original" enough to get copyright protection, or can be taken by others without being considered infringement. This is the scènes à faire doctrine.
"Stock scenes and hackneyed character types that "naturally flow from a common theme"—are considered "ideas," and therefore are not copyrightable. But as plots become more intricately detailed and characters become more idiosyncratic, they at some point cross the line into "expression" and are protected by copyright." Suntrust Bank v. Houghton Mifflin Co., 268 F. 3d 1257 - Court of Appeals, 11th Circuit 2001
See Amanda Schreyer's An Overview of Legal Protection for Fictional Characters: Balancing Public and Private Interests for many more cases and examples of the idea-expression dichotomy in action with respect to fictional characters.
I'm gonna say no you said you are writing a book about two alchemists heading to a tower to destroy the ring of evil, therefore there is no rip off of LOTR as you are telling a completely different story, this is why B movies which seem to blatantly rip off the plots of major blockbusters but change substantial elements of the story are allowed to proliferate. The only thing that copyright (and I assume you are talking about copyright) covers is the expression of the idea. So to answer your question with a fun Harry Potter example imagine that a wizard publishes a book of spells containing a the spell "Hocus Pocus" which transforms the target into a cat. After this book is published another wizard publishes another spell book which also contains the cat transformation spell, but this spell is named "Caturday" and described differently. The second wizard hasn't committed copyright infringement, as copyright merely covers the expression of the idea of a spell which transforms people into a cat and not the idea of transformation into a cat.
