M. Kate Stephenson is a lawyer at the law firm WeirFoulds LLP in Toronto and was called to the Bar in 1996. She has a litigation practice that focuses on human rights, constitutional, and administrative law. She has been counsel in several equality cases, often involving low income people and people on social assistance, often on a pro bono basis. In addition, she was seconded for two years (2002–2004) to the Clinic Resource Office of Legal Aid Ontario, where she was the clinic barrister, doing court litigation for clinics all across the province of Ontario. She was a member of the National Legal Committee of LEAF from 1999 to 2004, and she chaired that committee for two years.
As a law student, Ms. Stephenson was the director of the Centre for Spanish Speaking People's Student Legal Clinic, and presently, she is a board member of the Income Security Advocacy Centre in Toronto. In 2004 she received the first ever Advocates' Society Arleen Goss Young Advocates' Award; this award was created to acknowledge a lawyer who has been called to the bar for less than 10 years and who has demonstrated "innovative and passionate advocacy, contribution to social justice, and commitment to the community."