DJ Taylor: The victory for Dan Brown is a triumph for third-rate literature

To any one even remotely connected with the industry, Dan Brown's victory in The Da Vinci Code plagiarism suit was the most predictable event in publishing since the last Harry Potter soared to the top of the bestseller list. Copyright infringement cases are spectacularly difficult to prove - at any rate in the world of books - and most lawyers who took an objective view of last month's High Court proceedings were surprised that the case was even brought.

All that the defeated plaintiffs, Messrs Baigent and Leigh, can console themselves with, as they contemplate an estimated £2m plus legal bill (their own costs and 85 per cent of the opposition's) is the thought that the furore has shifted a few thousand more copies of their own bygone bestseller, The Holy Blood and the Holy Grail.

Mr Brown, on the other hand, can congratulate himself that he doesn't operate in a part of the cultural marketplace where they take these things seriously - or rather, in a part where plagiarism cases have a habit of being settled in the supplicants' favour. The music business, for example, is littered with the bones of blues guitarists who, having lifted some catchy riff from a vinyl 45 cut in the Mississippi Delta around the time of Eisenhower's election to president, have found their royalty pot substantially diminished by an unsympathetic judge. The legal protocols may be confusing - you cannot copyright a chord, but it is apparently possible to claim ownership of a short sequence of notes - but judgments tend to be decisive.

George Harrison, famously, paid a seven-figure sum to the composers of the Chiffons' "He's So Fine" for appropriating the central arrangement for his own "My Sweet Lord". Mid-'90s Britpop sensations Elastica were similarly taken to the cleaners by the Stranglers for reworking part of the latter's "No More Heroes", while Texas boogie band ZZ Top were embarrassed by John Lee Hooker's lawyers over a number called "La Grange" which, most neutral onlookers opined, fell into the honourable category of "respectful atmospheric tribute".

Back in the world of literature, the legal view of artistic "borrowings" is a whole lot more relaxed. For Dan Brown to immerse himself in the complex deductions of The Holy Blood and the Holy Grail may only be a case of third-rate literature cruising among the second-rate. And yet the upper reaches of the literary world are awash with senior figures cheerfully using the work of their forerunners as inspiration, if not outright template.

A key section of George Orwell's first book, Down and Out in Paris and London (1933), for instance, bears a notable resemblance to W H Davies's The Autobiography of a Supertramp (1908), mimicking its geography - a Saturday night low-life excursion into Limehouse - and its sequence of events. No one - certainly not Davies, who reviewed Orwell's book - was going to take Orwell to court; equally, without Davies, Down and Out could not have been written in quite the same way.

Fiction is just as susceptible to these ghostly derivations. Evelyn Waugh's Vile Bodies (1930) is always acclaimed as an original and definitive portrait of the rackety world of the Bright Young People, and yet one of its key motifs - the gossip-writer who invents his material - gestures at a lesser-known work by Beverley Nichols, Crazy Pavements, published three years before.

Taking sides in this complex round of influence-mongering is, consequently, a difficult business. No one who writes books for a living can have failed to heave a sigh of relief when Dan Brown emerged, figuratively speaking, into the sunlight beyond Court 61 with his reputation unbesmirched.

At the same time, it is worth remembering that there is such a thing as intellectual copyright and that the struggle to establish the fundamental right of owning the fruits of your own authorship took generations to achieve, with a heap of casualties lying by the wayside.

The line between influence-cum-inspiration and theft may a fine one, but it does exist. All of us - artist, audience and art itself - will suffer once it ceases to be drawn.