Footage taken during demonstrations outside energy firm Cuadrilla's exploratory oil drilling site at Balcombe, West Sussex, on August 19 last year showed the Brighton Pavilion MP being asked to move away from an emergency access where she was sitting with other protesters.
But Ms Lucas did not move as she wanted to show solidarity with the other protesters, the trial at Brighton Magistrates' Court heard.
An officer was heard asking her if there he was anything he could do which would make her move before she was arrested.
Lucas, from Brighton, is charged with wilful obstruction of the highway and breaching Section 14 of the Public Order Act.
Before the trial started, supporters gathered outside cheered as Lucas and her four fellow defendants walked up to the court building together. They stopped briefly outside as Sheila Menon, to read a statement on their behalf.
She thanked the people that had gathered outside for their support and claimed that Balcombe was just the start of a major struggle over the search and exploitation of fossil fuels and that the "stakes could not be higher".
All five defendants deny the charges and will argue that the section 14 notice was unnecessary, unreasonable and disproportionate. The trial continues.