Green party MP Caroline Lucas is to be charged with a public order offence after taking part in a sit-down protest against fracking last month.
The MP for Brighton Pavillion was among 30 protestors arrested in Balcombe, Surrey near where energy firm Cuadrilla had been drilling for oil.
The crown prosecution service (CPS) said Lucas would be charged with one count under the public order act and one count of obstructing a highway.
"After careful consideration, we have concluded that there is sufficient evidence and that it is in the public interest to prosecute Ms Lucas for breaching a police order on public assemblies and wilful obstruction of the highway,' said CPS lawyer Nigel Pilkington.
The protest was organised by the No Dash for Gas campaign who are opposed to the controversial method of extracting gas through pumping water into drill sites.
Protests began in Balcombe after Cuadrilla received planning permission to drill a 3,000 feet well close to the village.
Lucas today defended her decision to take part in the protest.
"I firmly believe in the right to peaceful protest and remain deeply concerned about the impact of fracking on climate change and the wider environment," she said.
"I have been advised by my lawyer to make no further comment at this stage."
Lucas is the former leader of the Green party. The party's current leader Natalie Bennett told Politics.co.uk that Lucas had been right to act as she did.
"As Caroline said when she was arrested, sometimes it's very hard under our very strained non-functionaing political system to get voices heard," she said.
"The Green party has been a supporter of non-violent direct political action over a number of years and sometimes that's a necessary part of the political process."
Lucas will appear at Crawley magistrates court next month.