Caroline Lucas MP will be prosecuted on two charges, one for breaching a police order on public assemblies and another for wilful obstruction of the highway.
Nigel Pilkington, a senior lawyer with the Crown Prosecution Service South East, said:
Following an investigation by Sussex police, the Crown Prosecution Service has received a file of evidence in relation to Ms Caroline Lucas MP.
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.
These are summary offences which can only be tried at Magistrates' Court.