The employees claim they have been retaliated against for their support of Dart's opponent in the 2006 primary election.
All of the plaintiffs were part of the department's elite special operation response team.
The suit claims they were disbanded two weeks after the election for political reasons.
Dana Kurtz, an attorney for the employees, explains how their lives have changed.
"Denials of promotion, discipline, being put back at the jail, being denied opportunity for advancement, having their lives destroyed," said Kurtz.
Opening statements in the case were delivered Monday.
The Cook County Sheriff's Office released this statement regarding the trial:
"The Cook County Sheriff's Office is very proud of the fact that it is the only local government office that has been declared in compliance by the federal courts and therefore is no longer monitored by the courts or their appointed monitors. The office worked hard during the monitoring process and is proud of its ethical integrity. It cannot be stressed enough that this was a federal court decision to free the sheriff's office of the monitor, based on the hard work and policies implemented by the dart administration.
"This specific case started over six years ago during a previous administration. Not one of the individuals suing the county was fired and some were promoted. It is beyond perplexing that these individuals are suing for more money when they already have had every opportunity for promotion. Sheriff Dart and his office proudly stand on their record."