ONDON — Since the revelations of plagiarism by the popular historians Stephen Ambrose and Doris Kearns Goodwin, commentators have been wrestling with the nature of literary theft. It's been interesting to see this from my vantage point as the so-called wronged party in the Goodwin case. Ms. Goodwin's book, "The Fitzgeralds and the Kennedys," contained many sections that were copied from my book, "Kathleen Kennedy: Her Life and Times."

I discovered this in the course of doing a review of Ms. Goodwin's book. I was shocked to read passage after passage of my own book embedded in hers. I wrote a kind review, then hired a copyright lawyer. We eventually reached a satisfactory settlement.

There have been a great number of attempts to explain away plagiarism as a justifiable act with plenty of artistic and historical precedent. In some quarters, it has been excused as the literary equivalent of the droit du seigneur — the natural entitlement of the most talented or the most popular writers who can have their way with whatever material happens to seize their fancy.

But the popularity of the authors, their intentions, their track records, the quality of the book from which the plagiarized material was lifted, the tendency of journalists themselves to make a hash of the facts — all of these issues are beside the point.

Topics  Alerts Books and Literature Writing and Writers Goodwin, Doris Kearns Create Your Own | Manage Alerts Take a Tour Sign Up for Newsletters Authors in Depth: V. S. Naipaul Read now for just $4.95. A Trinidad-born English writer, Mr. Naipaul was awarded the 2001 Nobel Prize in Literature. This retrospective includes New York Times reviews and interviews with the laureate.

Plagiarism is the dishonorable act of passing someone else's words off as your own, whether or not the material is published. Merely footnoting the copied words does not cure the wrong. In cases where the words are protected by copyright, copying in more than minimal amounts is illegal, regardless of whether the copying was unintentional.

Writers don't own facts. Writers don't own ideas. All that we own is the way we express our thoughts. Plagiarism pillages unique expressions, specific turns of phrase, the unusual colors a writer chooses to use from a personal literary palette. Of course, in popular histories familiar facts and scenes are often retold, but this is not plagiarism if the telling is done in a writer's own words.

A case brought by Harold Courlander, author of "The African," against Alex Haley for the use of his material in "Roots" involved a claim of copyright infringement, but the case hinged, in part, on the use of three words. The author of "The African" wrote that the ship "pitched, rolled and trembled." Haley's book contained the identical phrase — one so individually wrought that it was highlighted at the trial as evidence that other material had been copied too. That case was eventually settled.

In my case, whether Ms. Goodwin had used footnotes or even quotation marks around the passages taken from my book would not have mattered. (Some passages were credited to me in footnotes.) It was the sheer volume of the appropriation — thousands of my exact or nearly exact words — that supported my copyright infringement claim.

Recognizing the thieving tendency of creation, copyright law does allow a bit of leeway. Under some circumstances one is allowed to quote a modest number of words from someone else's work. Writers, after all, are relentless scavengers, searching in the flotsam and jetsam of their daily experiences for a surprising turn of phrase, a fresh metaphor.

But it is important not to excuse the larger sins of appropriation. In this age of clever electronic tools, writing can easily turn into a process of pressing the cut-and-paste buttons, or gluing together the work of a team of researchers, rather than the long and lonely slog of placing one word after another in a new and arresting way.

Without demanding that writers, famous or struggling, live by a certain literary law and order, we may gradually lose the notion that an individual's unique expression matters.

Lynne McTaggart is the author of the forthcoming "The Field: The Quest for the Secret Force of the Universe.''