Clearer cases in nonfiction

Plagiarism is often more clear-cut in nonfiction, but there are murky areas. Copyright experts often argue that ideas and facts aren’t subject to intellectual property protection, unlike the extensive use of precise language and phrasing, so plagiarism is often treated as an ethical infraction rather than a legal one. Jill Abramson, the former executive editor of The New York Times, recently faced accusations that she had plagiarized passages of her new book, “Merchants of Truth.” She acknowledged that some passages lacked attribution and would be corrected in future editions, but defended her work over all by noting that “all of the ideas in the book are original, all the opinions are mine.”

Even in fiction, there are precedents in copyright law where the borrowing of plot elements is so extensive and blatant that plagiarism crosses into copyright infringement.

“The courts hold out the possibility that it could be infringement without a language overlap,” said Rebecca Tushnet, an intellectual property expert at Harvard Law School. “If you did the exact same things in the exact same sequence all the way through, the court wouldn’t have that much trouble finding infringement.”

Ms. Tushnet said the plot parallels between Mr. Mallory’s novel and “Saving April” were “likely too thin to support an infringement claim,” since some of the plot points at issue — like the unreliable female narrator and a young victim who turns out to be a perpetrator — are well-worn tropes in thrillers.

Ms. Denzil, who lives in Yorkshire, England, started working on “Saving April” in October 2015, and finished a draft in eight weeks. When she released the novel in March 2016, it received largely positive reviews, and became a best seller on Amazon in the United States and Britain. It went on to sell over 120,000 copies, and has more than 6,800 ratings on Goodreads.

But two years later, some online reviewers began noting that “Saving April” was a lot like “The Woman in the Window,” by A.J. Finn, a pen name for Mr. Mallory.

The stories cover starkly similar territory (spoilers follow).

The protagonists of both novels are middle-aged women — Hannah in “Saving April,” and Anna in “The Woman in the Window” — who suffer from intense anxiety and are afraid to leave their homes, and begin spying on their neighbors, in both cases, an unhappily married couple with an adopted teenage child who has a troubled past. In “Saving April,” the teenager is a girl whose birth mother was a neglectful alcoholic; in “The Woman in the Window,” the adopted teenager is a boy whose birth mother was a neglectful drug addict.