Former Thai Prime Minister Yingluck Shinawatra has arrived at court in the capital, Bangkok, for the start of her trial on negligence charges.
She is accused of dereliction of duty for her role in a controversial rice subsidy scheme.
If found guilty she faces a maximum prison sentence of 10 years.
Ms Yingluck, who was forced to step down last year, has denied the charges against her, saying they are politically motivated.
Arriving at the Supreme Court on Tuesday, she told journalists she was confident that she would prove her innocence.
Last week she said she was ready to defend herself in her opening statement, Thai newspaper The Nation reported.
Thailand's Constitutional Court forced Ms Yingluck from office in early May 2014 after finding her guilty of abusing her power. Weeks later, the military seized power saying it needed to restore order following months of street protests.
'Support for poor'
In January this year, Ms Yingluck was retroactively impeached by a military-appointed legislature for her role in the rice subsidy scheme. She was also banned from politics for five years.
The scheme paid rice famers in rural areas - where her party has most of its support - twice the market rate for their crops, in a programme that cost the government billions of dollars.
Ms Yingluck says she was not involved in the scheme's day-to-day operations and has defended it as an attempt to support the rural poor.
Ms Yingluck's brother, Thaksin Shinawatra, was removed by a previous coup in 2006 and now lives in self-imposed exile.
But the influence of the family persists, with parties allied to the Shinawatras winning every election since 2001.
They are loved in the rural north for their populist policies, but hated by the country's elite who accuse them of corruption.
