Tommy Robinson refused to hand over his phone pin when police stopped his Bentley on the way to Benidorm, a court has heard.
He allegedly told officers "Not a chance, bruv" and said he was a journalist when they pulled him aside at the Channel Tunnel at Folkestone in July 2024.
Robinson , real name Stephen Yaxley-Lennon, is accused of "frustrating" counter-terrorism powers by refusing to give access to the phone.
He denies the charge.
The right-wing political activist was flanked by security guards as he arrived at Westminster Magistrates Court for the opening of the trial on Monday.
The 42-year-old faces three months in prison and/or a £2,500 fine if found guilty.
Robinson had £13,000 and 1,900 euros on him when he was stopped and told police he was going to Benidorm in Spain for