Prosecutors have said Mr Linehan harassed Ms Brooks on social media, accusing her of a "homophobic attack" by being involved in the disruption of an LGB Alliance conference on 11 October 2024 when thousands of live crickets were released.
His messages were "not merely irritating or annoying, but rather oppressive and unacceptable, thereby crossing the threshold into harassment", Julia Faure Walker, for the prosecution, said on Thursday.
Mr Linehan is also accused of damaging Ms Brooks's phone when she tried to confront him outside the Battle of Ideas conference in London on 19 October last year.
The prosecution alleged that Mr Linehan "deliberately whacked" Ms Brooks's phone out of her hand after she filmed him while challenging him over his previous posts.
A video played to the court appeared to show Mr Linehan grabbing the complainant's phone.
In his evidence, Mr Linehan said the complainant was "invading my personal space" at the event, and was being "incredibly annoying and persistent".
"My adrenaline was up. I felt angry," he said. "I took his phone, put it behind my back. I could see he was furious. Then I threw the phone."
He didn't want to damage the phone, he said. "I didn't slam it, I just skimmed it. It was instinctive. As soon as I did it I thought, that was a mistake."
There were heated exchanges during cross-examination when Mr Linehan demanded to know whether the prosecutor thought the complainant "is a female".
At one point, the judge called for a break because "the heat in here has risen, and I don't just mean the temperature".
After the conclusion of Friday's evidence, the case was adjourned until 29 October, with Mr Linehan released on bail.