This week’s Harry Potter court decision in New York is well worth reading for anyone who’s interested in knowing whether something is fair use or an illegal copyright infringement. The case involved an unauthorized lexicon of the Harry Potter books that was to have been published as a book last fall. (The book was adapted from a free web site edited by the lexicon’s writer.) J. K. Rowling and Warner Brothers, who created the Harry Potter books and movies, sued. The PDF of the resulting court decision has been posted at Groklaw, which also has a text version with commentary. There’s also some interesting discussion on Teleread, including a long comment from someone involved in a similar case with a different outcome.

Neither side got all they wanted in the Potter case. The judge, Robert Patterson, ruled that the lexicon violated Rowling’s copyrights, put the kibosh on the book, and fined the publisher. But he imposed the minimum fine prescribed by statute, and made it clear that, contrary to Rowling’s claims, other people were welcome to publish lexicons and other nonfiction books that comment on Harry Potter or other works of fiction, without having to get the copyright holder’s permission. They just had to be more sparing in their reuse of the work than the author of this lexicon was.

A key question in the case had to do with the purpose of the book at issue. Was it “transformative”; that is, was it trying to do something essentially new and original, using the older work as base material? Or was it simply a rearrangement of the work, or derivative variation on a theme? Fan fiction, for instance, is usually considered derivative rather than transformative work (since it, like the original it’s based on, is typically a story meant for entertainment, based on the same characters, settings, and plot structure.) As a derivative work, it gets minimal fair use protection. Likewise, in the same circuit that decided the Harry Potter case, an unauthorized Seinfeld trivia game was ruled not to be fair use, since it simply retold imagined events from the TV show in a new arrangement, without adding significant original content. (The Seinfeld case, known as Castle Rock vs. Carol Publishing, was repeatedly cited in the Harry Potter decision, as were a number of “unauthorized guidebook” cases.)

Patterson ruled that a lexicon was transformative use of Rowling’s novels, since a set of stories was transmuted into a reference guide that included original commentary on the story elements. Unfortunately, there wasn’t that much original commentary in the lexicon, and the amount of material quoted from Rowling was a good deal more than what was needed for that commentary, the judge ruled. (Note that I have not read the lexicon myself; for the purposes of this post, I’m relying on Patterson’s findings of fact.) Moreover, the lexicon also borrowed heavily from two companion volumes by Rowling, Quidditch Through the Ages and Fantastic Beasts and Where to Find Them, that already were very similar in form and intent to the lexicon.

A pure lexicon could simply have had short definitions (say, 1 or 2 sentences of original prose) for each character or concept in Rowling’s books, and then simply cited places in Rowling’s works where the character or concept appears or is further described. Instead, all too often the author apparently wanted to mention everything significant Rowling had to say about things in the lexicon, and borrowed extensively from Rowling’s text, either literally quoted or closely paraphrased. (Paraphrasing doesn’t avoid the problem of copyright infringement, if you’re still copying the author’s imagery or other original expression.)

Extensive reuse of Rowling’s expression might still have been okay if the author needed to comment specifically on that expression. (For instance, a critic might quote Rowling’s use of imagery for magical spells to compare it to, say Tolkien’s imagery for the same concept.) But too often, the copying of Rowling’s expression in the lexicon was not used to back up original commentary by the author, but was used instead of original comment. This happened often enough, Patterson decided, that he could not uphold a claim of fair use.

The lexicon’s publication as a book sold commercially, as opposed to its earlier form as a noncommercial website, was also a factor in the final ruling. But it wasn’t as decisive as one might imagine, and the judge devotes relatively little text in the decision to this factor. Even a commercial book on Harry Potter can be fair use; and a noncommercial website on Harry Potter (such as one that posts complete copies of Rowling’s books) can be infringing.

The take-away from this decision is that authors of commentaries and guides to other works of fiction can proceed in many cases without permission, provided that they’re making significant original contributions to readers’ understanding of the works they comment on, and that they reuse or quote only what is necessary to provide these contributions. In other words, if you’re writing one of these guides, the focus should be on what you’re giving to the reader, rather than on what you’re taking from the earlier writer.

Online opinion of Patterson’s decision has been mixed, with some applauding the final ruling and some arguing against it. I’m not a lawyer, and don’t presume to say whether he got the ruling exactly right. But I think his extensive discussion of the facts and precedents behind his decision provides a valuable guide for writers who want to maintain the proper and legal focus in their own fair use of others’ work.