Library closures across the country are challenged for the first time at the High Court today.
Campaigners are seeking a ruling that decisions to close six libraries in the London borough of Brent are legally flawed.
The Brent case is expected to be followed in the near future by similar challenges to library cuts proposed by Gloucestershire and Somerset county councils, and on the Isle of Wight.
Nick Cave, Depeche Mode, the Pet Shop Boys and Goldfrapp are among those who have contributed to campaign legal costs.
Playwright Alan Bennett launched a scathing attack when he spoke at a church benefit to raise legal funds to save Kensal Rise library, one of the six under threat in Brent. He compared the loss to "child abuse".
Brent campaign lawyers are applying for judicial review, arguing council officers unlawfully failed to assess local needs and the likely impact of closing half the borough's libraries.
In particular, not enough was done to check on the views of nurseries and schools, some of which are dependent on local libraries to give pupils access to books.
The campaigners have condemned "the wholesale rejection" of a number of proposals for running libraries jointly with local community groups to cut costs.
Margaret Bailey, one of the campaigners bringing the judicial review claim, said: "The threatened libraries are important for everyone who lives, studies or works locally, but especially for low income families and their children."
She said the proposed cuts, ordered by the council's executive committee in April, "make no sense legally or otherwise".
John Halford, of Bindmans LLP, the solicitors representing the campaigners, said: "Brent sought to characterise its proposals as a 'transformation' of library services, but in reality it has simply swung a wrecking ball through local services with little regard to the consequences for those who use them."
The Government has faced criticism from the author Kate Mosse over its refusal to intervene in library closures around the country.
She told The Independent: "There has been a naive belief on the part of government and local authorities that after the initial objections, public anger would wane. Instead it is the precise opposite: the anger has simply exacerbated."
She said there had been "a catastrophic failure of leadership" from the Museums, Libraries and Archives Council, the Arts Council and the Department for Culture, Media and Sport (DCMS).
A DCMS spokesman said: "We continue to monitor and assess proposals and decisions being made about changes to library services across England.
"We take very seriously compliance by local authorities with their statutory duty to understand the local needs for library services and to provide a comprehensive and efficient service to match that need."