Alok Mukherjee, the chair of the police services board, shared a Facebook post from the group Occupy Wall St. with the caption "I can't breathe."
"I can't breathe" were the final words of Eric Garner, a man who died while New York City police were applying a choke hold to him this past summer.
Those same words have now been adopted by protesters demonstrating against a decision by a grand jury in New York not to indict the officer who applied the choke hold.
The police union are saying the since-deleted post is enough to call for the resignation of the Mukherjee.
The post was accompanied by a composite image altered with text to display the following:- An image of ISIS, with the caption "Americans killed by ISIS: 3"
- An image of a strand of the Ebola virus, with the caption "Americans killed by Ebola: 2"
- An image of a protest, with the caption "Americans killed by police: 500+ every year"
The union representing the Toronto police say the post "crossed the line."
"His lack of objectivity indicates he is no longer fit to sit on a police oversight body," said union representative Mike McCormack. "His sharing of this poster is clearly unprofessional, clearly unethical and clearly seeks to undermine the very people he is paid to oversee."
McCormack has vowed to file a complaint against Mukherjee to premier Kathleen Wynne and mayor John Tory. Mukherjee is appointed to the board by the province.
Mukherjee will respond to the complaints later on Friday.
This is not the first time Mukherjee has been at odds with members of the Toronto police.
He has clashed with police chief Bill Blair and the union over budget figures and racial profiling. Mukherjee and police representatives have been both been very public in their disputes in recent months.