The Socialist TD Paul Murphy is among 4 people arrested in connection with a protest in Jobstown in Dublin last November which saw the Tánaiste trapped in her car for several hours.
The men - aged between 30 and 50 - have been detained at a number of Garda stations across the southside of the city under Section 4 of the Criminal Justice Act.
They can be held for 24 hours.
The incident happened after 100 protesters circled the Tainiste's car as she was leaving a graduation ceremony for students in Tallaght.
She was trapped in her car for more than three hours during the incident. Gardai had to transfer her to 3 different cars before she managed to leave the area.
