An anti-HS2 protester scaled a mechanical tree lopper in an attempt to protect ancient woods, a court heard.
The transport secretary and HS2 Ltd allege Elliott Cuciurean, 22, breached an injunction 17 times in Crackley Woods, Warwickshire, this year.
Together they have brought a case at Birmingham High Court to have Mr Cuciurean, from Cheltenham, jailed.
The campaigner claims there was “confusion” about what land was covered by the court order.
Video footage shown to high court judges showed Mr Cuciurean, also known as Jelly Tot, on top of the tree lopper and, in a separate incident, being removed from a tree via the use of a cherry picker.
He was described as “a very active protester” and told the court he scaled the machinery because it “is going to continue cutting down trees so I will do what I can to stop it’.”
He said he arrived at the protest camp which neighbours the work site on 4 April and would walk the perimeter “to keep an eye on things”.
HS2 Ltd claim Mr Cuciurean breached an injunction on an area of land within an 8km (4.9-mile) perimeter at the Crackley Woods construction site.
The activist told the high court he did not see injunction warning notices in the area and was never informed of the detail of the enforcement.
However he admitted he had moved fences around the site and was there “to stop the work”.
High court enforcement officer Gary Bovan, who had been at the woods throughout April, said it was “very important” to know Mr Cuciurean’ location on the site because “he’ll go and find out all of the site, work out weak places and hotspots”.
Judgement is expected to be reserved until a later date.