They want know if there was an equipment defect and look at surveillance video from Thursday's incident.
The lawyers say Bernier was boarding a bus on the 1100-block of South Michigan when the doors closed on her. Her attorneys say she was trapped and dragged for a block before the driver finally stopped. She's hospitalized for treatment for her injuries.
The CTA says the incident is being investigated, but can not confirm that Bernier was dragged.