Officer Bernard Butler's suspension was approved by a 5-4 police board vote.
SEE ALSO: Videos of police shooting at CTA Red Line station released by COPA
Butler and his partner, former Officer Melvina Bogard, struggled with the man at the Grand Red Line station before Butler allegedly told Bogard to shoot the man, who was critically injured in the incident.
Bogard was acquitted on criminal charges but has since resigned from the police force.
Cell phone video captured the entire incident at the time.