Kassia Bonisteel

Lawyer, she/her/hers



Practice Areas

Labour Law

A UPFH partner, Kassia Bonisteel is a determined investigator able to marshal complex facts and evidence in support of the trade unions, associations and individual employees she commonly represents.

Kassia’s practice encompasses labour law, employment law and civil litigation. She has particular expertise navigating fitness for duty cases often involving drug testing by employers; employment privacy cases; sexual and other harassment, discrimination and assault matters; and interest arbitrations. In addition to having in-depth knowledge of various constitutional issues related to drug testing, she is expertly familiar with the leading science on drug impairment and drug testing mechanisms, including methodological assessment of experiment design. 

Kassia has represented union members in various fitness for duty, privacy, assault and  harassment grievances. In a notable case involving an employer’s Twitter account being used by members of the public to publish vulgar, offensive, abusive, racist, homophobic, sexist and threatening tweets about employees, the union she represented was successful in arguing that social media sites operated by the employer can be considered part of the workplace and that the employer had failed to take all reasonable and practical measures to protect employees. 

Kassia is a member of the Canadian Association of Labour Lawyers (CALL) and the Ontario Bar Association. She holds her JD from the University of Ottawa and her BA (Honours) from University of Toronto, graduating with High Distinction and receiving the Certificate of Academic Excellence. 

Decisions of Interest

Canadian Union of Skilled Workers v. Bruce Power, 2018 CanLII 13995 (ON LRB)

  • A grievance in which Kassia was co-counsel on a team that successfully challenged Bruce Power’s revocation of the security clear of a union member working at a nuclear generating plant.

Amalgamated Transit Union, Local 113 v. Toronto Transit Commission, 2018 CanLII 69588 (ON LA)

  • As co-counsel, Kassia successfully litigated on behalf of an employee who was wrongfully terminated for making a complaint of sexual harassment and assault perpetrated by her supervisor.