Salvador Reza, a migrant rights advocate, says he was wrongfully arrested and is suing Maricopa County Sheriff Joe Arpaio.
Reza was arrested on July 29, the day SB 1070 took effect.
As part of his release conditions for his first arrest, a judge forbid him from making contact with any arresting officers.
The next day, Reza arrived for another protest.
The Maricopa County Sheriff's Office says deputies recognized him and contacted court officials to check on the conditions of Reza's release.
Reza, an organizer with the Arizona-based Puente Movement, claims he never took part in the protest outside Arpaio's jail and was just watching from across the street.
The case was dismissed because both the judge and prosecutor agreed there was no evidence of any probable cause.
Arizona Immigration Law - Senate Bill 1070: