The first Michael Mullins knew of his son's suicide being depicted in a poem was when he read a review in his local newspaper. It was the Galway Advertiser, the same newspaper that 18 months before carried the notice of the teenager's tragic death.

The poem, Black Dog in My Docs Day, had been written by Rita Ann Higgins, a local poet. She was also Mullins's sister-in-law. The reviewer quoted part of the verse, which named the young Mullins, described how he had been in a psychiatric unit, and how he had spoken to Higgins about killing himself.

To have his son's private details and conversations published in a book was deeply upsetting for Mullins. His marriage to Higgins's sister, Bernie, was annulled many years ago. Still he felt he should have been consulted or shown a draft copy of the poem prior to its publication.

Mullins contacted a solicitor, and had legal letters sent to Higgins and her British publishers, Bloodaxe Books. He wanted further publication of the book stopped unless the poem was removed or altered. Mullins said he did not object to the whole poem or that the book was dedicated to his son, but to the "unnecessarily graphic, cold and hurtful nature of some of the passages" which "could have been rewritten so as not to cause distress and offence".

The passages to which Mullins objects are a small part of a lengthy poem which summarises his son's life until his suicide, aged 18, in December 1999. Higgins describes how he was hospitalised as a baby with meningitis, the day he made his holy communion, and when he was confirmed - "you took Hercules as your middle name".

She remembers helping him fill in an application for a passport, dying his hair blue, and when his school mistakenly said he had failed maths. "You went in yourself to set the record straight./Your mother has the letter of apology the school sent." It recounts his struggle with depression, including treatment in a psychiatric ward, and the thoughts of suicide he discussed with his aunt.

Throughout the poem Higgins names 30 relations, friends and neighbours that miss Mullins, including his Aunty Carmel in Florida. Nowhere in the 950 or so words is his father named.

Not surprisingly, the Galway poet has refused to rewrite the verse, and points out that her sister, the boy's mother, was not offended by it. The passages Mullins complained of were "out of context" with the sentiment of the poem as a whole. "It is really a love poem in memory of my nephew and wasn't intended to offend anyone," she said.

So is this legal quarrel just the result of a family feud or does it have wider implications for artists who raid real life for their art? Does artistic freedom mean writers can say whatever they want about a real person in fiction?

"Where would I draw the line if I started rewriting my poems?" Higgins has demanded. "All my poems are about people. But I suppose it's not the first time my poems have att-racted solicitors' letters."

Higgins, 46, has indeed taken poetic licence before. The KKK of Kastle Park led to a local residents' association threatening her with legal action. Workshops in Portlaoise prison were cut short after another ode caused offence. After a period as writer in residence at University College Galway, Higgins penned a sharp poem about life in academia. The college authorities are understood to have been unimpressed.

"In a way this row was so predictable," said Jessie Lendennie, co-founder and managing director of Salmon Publishing, who first discovered Higgins's talent and published four books of her poetry. "It is in her style - tell it like it is. But this poem has scratched an old wound and relates to a history of bad feeling."

Lendennie reveals that Higgins also wrote candidly about her father, with whom she had a difficult relationship. He, too, was annoyed at becoming his daughter's muse. "There was a time when he was upset but it blew over when he saw what she had accomplished," said Lendennie.

Higgins's first four books sold 10,000 copies, about five times more than usual. She is particularly popular in America. Reviewers call her gutsy, anarchic and explicit. Typical of her work, dominated by social commentary, is The Trouble with Karen Reilly, about the woman shot dead by Private Lee Clegg in Northern Ireland. It ends: "She was wild/ she was free/ she was Bon Jovi/ with the bullet in her back/ she was Clegged."

Casual readers picking up An Awful Racket, her latest collection, are warned that Higgins is untameable, spiky and upfront. Reviewers said the collection was not for the faint-hearted, describing its language as savage, its imagery as stark.

Lendennie insists that Higgins's poem about her favourite nephew was not exploitative. "She just has to do that, and people identify with that in her work. She could not not have written this poem."

Still, the publisher admits that she would have thought hard about including Black Dog in My Docs Day in a collection. "I might have questioned it, whether it should go into a volume or not," Lendennie said. "But I don't think the poem is malicious. It would be obviously objectionable if a writer exploited other people's experiences, but Rita Ann does not do that. She does have a soft caring side too; she is no haridan."

Higgins's supporters are pointing to similarities with Mid-Term Break, one of Seamus Heaney's best known poems in which he wrote about the death of his four-year-old brother in a car accident - "In the porch I met my father crying/ He had always taken funerals in his stride". Such is the lyrical beauty of the Nobel prize winner's verse, however, that it would seem almost sacrilegious to complain about its inspiration.

The legal dispute between Mullins and Higgins is expected to be settled out of court, but as the lines between fiction and faction continue to blur, it seems inevitable that a judge will some day be asked to decide where does art stop and intrusion begin.

OTHER Irish authors have been accused of exploiting tragedy to enrich their writing. Eoin McNamee wrote a fictionalised account of the Shankill Butchers in a novel, Resurrection Man. Though all the names were changed, relatives of the loyalist gang's victims were still upset because the murders were so recent.

McNamee is already embroiled in more controversy. His new novel, The Blue Tango, is based on the 1952 murder of Patricia Curran in Northern Ireland. Due for publication next month, it appears to add a thin veneer of fiction to well known events and this time the real names of the main players are used. McNamee even suggests an alternative murderer to Iain Hay Gordon, the Scot who was wrongly convicted of the crime. Rarely have the lines between fiction, non-fiction and faction been so blurred.

But then, even William Butler Yeats upset people he wrote about. One of his poems, Reprisals, was withheld at the request of Lady Gregory, his patron, because she did not like allusions to her dead son. "The poem was suppressed because Lady Gregory felt it besmirched the memory of somebody who died in tragic circumstances," said Anthony Roche, a lecturer in literature at University College Dublin. "It is not unlike the situation with Higgins's poem.

"There is a belief that everything is fair game in a work of art, that it has its own rules, procedures and integrity, and it should be judged by that. However, there are other issues, of aesthetics, ethics and taste. It's a complex phenomenon and writers in the public sphere consider what to put in and what to leave out every step of the way."

Sylvia Plath never erred on the side of caution. She described the death of a neighbour in her diaries, and then used it as inspiration for her poem Berck-Plage which included a description of the neighbour's stiffening corpse.

While dead men can't sue, the laws of libel do protect living people who find themselves depicted in works of fiction. The publication of Dubliners was delayed for years because James Joyce had included real people's names and actual locations instead of invented ones. The author believed it added to the work's authenticity.

Oliver St John Gogarty successfully sued Patrick Kavanagh, the Monaghan poet, for libel over a throwaway remark about him in his novel The Green Fool. Kavanagh had said of his reception at Gogarty's door in Dublin: "I mistook Gogarty's white-robed maid for his wife - or his mistress. I expected every poet to have a spare wife."

Modern writers continue to plunder the lives of those around them for fictional purposes. Hanif Kureishi, who left his wife and children, was accused of writing a personal confession in Intimacy, a novel about a man who leaves his wife and children.

"Of course it's fiction," Kureishi insisted. "It's irrelevant where it all comes from. Some stuff came from me, lots from other people. I can't remember which was which."

Literary agents admit that most first novels submitted are autobiographies, thinly disguised. Some authors actually confess that real people feature in their work.

Kate Thompson, author of It Means Mischief, said she sometimes bases minor characters on people she knows. "Sometimes I put people in to get revenge but they will only be peripheral and be heavily disguised," she said.

"If somebody dissed me big time I could put them in a book and get a great deal of vicarious pleasure out of it. There is no way they could recognise who it is, though. I would never base major characters on real people."

Using real people is more dangerous in thinly-populated Ireland than in the anonymity of Britain or America, as Roche points out. "It goes back as well to the notion in Irish society of writing as a form of betrayal, that to write a thing down is like informing on somebody," he said.

"In a way Rita Ann Higgins speaks with a very local sense of her community and speaks to a larger audience through the medium of print - some of those tensions are perhaps coming up in this situation."