The director of Moscow's Library of Ukrainian Literature has gone on trial charged with inciting ethnic hatred against Russians.
Natalia Sharina is accused of disseminating banned literature classed as extremist.
She denied the charges in court and her lawyer told the BBC he believed the case was politically motivated.
The trial opened with a feisty exchange between the librarian and the state prosecutor.
First the prosecutor cited a long list of Ukrainian publications that are either prohibited or which she said experts had deemed "degrading" to Russians.
She formally accused Natalia Sharina of acquiring the books and brochures and a CD and making them available to the public.
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"I do not understand the charge and so I do not feel any guilt," replied the library director, dressed in a long cardigan and grey brogues.
"I ask the respected prosecutor to explain what actions I actually took to spread enmity," she added, demanding to know what possible motive she might have had.
Mrs Sharina, 59, also denies a second charge of embezzling library funds.
Her lawyer says witness statements describe seeing officers planting banned books at the library when they arrived to search the premises in October 2015.
"It's very sad that someone is trying to drag this court into politics," Ivan Pavlov told the judge.
Outside, the lawyer told the BBC he believed the case was "steeped in politics", adding that was true of everything to do with Ukraine now.
Relations between Moscow and Kiev are still at an all-time low after Russia annexed Crimea and pro-Russian forces seized power in parts of eastern Ukraine in 2014.
"It's no coincidence that it's the Ukrainian literature library that was searched, and not a Belarusian or a Cossack one," Mr Pavlov argued.
The trial was adjourned for three weeks and Natalia Sharina will remain under house arrest, as she has for over a year.
She was only recently allowed out for a daily walk and is banned from speaking directly to journalists.
If the librarian is eventually found guilty, she could be facing well over a decade behind bars.
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