Sticky subject, this plagiarism, not simply because it’s an issue of ethics, or because the legalities of copyright infringement are often vague, but because many accusers don’t even understand what it is.

Most of the time these cries of plagiarism never make it into court. Neither the guilty nor the aggrieved have that sort of money so authors are simply named and, if the mud sticks, shamed. After Graham Swift won the Booker Prize in 1997 for his novel Last Orders, University of Melbourne academic John Frow “exposed” his appropriation of the architecture of the great William Faulkner’s As I Lay Dying. Like Faulkner, he revealed, Swift told his story by adopting different voices for a series of first-person narratives.Swift was astonished; the homage to Faulkner emerged in the process of writing and was, in his eyes, so obvious that he had thought every literate person would simply appreciate it and move on. In every other respect, Last Orders was clearly a very different book. The furor was soon over, in fact, but it made Swift’s life fairly hellish for a week or two. “It is in the nature of literature that books may derive from or be influenced by others,” he said at the time. “Equally, there are certain things for which there is no literary patent or monopoly.”

And then, of course, there’s Ian McEwan, who, earlier this week, was accused of lifting parts of his novel Atonement from Lucilla Andrews’ autobiography No Time for Romance. In McEwan’s case, it’s less a question of plagiarism and more about the appropriation of research. But the line is further blurred because of McEwan’s rewording of some passages in Andrews’ book.

In one example quoted, Andrews wrote of “dabbing gentian violet on ringworm, aquaflavine emulsion on cuts and scratches, lead lotion on bruises and sprains.” Accordingly, McEwan’s heroine Bryony “had already dabbed gentian violet on ringworm, aquaflavine emulsion on a cut and painted lead potion on a bruise.” The dolls on which Andrews practiced blanket bathing were called Mrs. Mackintosh, Lady Chase, and George; so were Bryony’s. And so on.In a sense, the trap of quotation awaits any novelist who wants to use the past. “It is an eerie, intrusive matter, inserting imaginary characters into actual historical events,” McEwan wrote in The Guardian newspaper a few days after he stood accused. “

As one crosses and re-crosses the lines between fantasy and the historical record, one feels a weighty obligation to strict accuracy … There is no escape: Dunkirk or a wartime hospital can be novelistically realized, but they cannot be re-invented.” There was, in fact, very little information available at all about nursing of the time; most war histories were military or political. “For certain long-outdated medical practices, [Lucilla Andrews] was my sole source,” he continued. “I have always been grateful to her.”

This is not a dispute that will make it to court. Legally, copyright is infringed only by material that is “important, distinctive, or essential” to the original work, according to the senior legal officer at the Australian Copyright Council, Ian McDonald. “It’s not just a question of amount. In most cases where there is a question of infringement, the author has taken a little bit from here and a little bit from there; it becomes an ethical matter rather than a legal one.” McEwan’s Atonement, he says, falls into that category.