Brooks is in the dock along with seven other defendants, including her racehorse trainer husband Charlie and British Prime Minister David Cameron's former director of communications Andy Coulson.
The case is scheduled to last until next April as around 100 witnesses have been summoned.
Brooks and Coulson are accused of conspiring with others to listen to voicemails and commit misconduct in a public office.
The trial will begin with jury selection today and focus on allegations of wrongdoing at the Rupert Murdoch owned 'NoW' before it was closed down in July 2011 after claims that journalists had hacked the mobile phone of murder victim Milly Dowler.
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Other defendants are Stuart Kuttner, a former managing editor of 'NoW'; Ian Edmondson, a former head of news; Cheryl Carter, Rebekah Brooks's former secretary; Mark Hanna, head of security for News International; and Clive Goodman, a former 'NoW' royal correspondent.
All eight have pleaded not guilty to the charges.
The landmark case is expected to grab high-profile worldwide media attention but the UK judicial system bans any comment on active trials until the verdict has been delivered.