Prior to his appointment, Justice Black practiced litigation with McCarthy Tétrault in Toronto (1989-2021). His practice has involved defending medical malpractice claims and complaints, and a wide array of commercial litigation for both plaintiffs and defendants, in recent years including in particular advising and representing accounting firms. In his 32 years of practice, he has regularly appeared at all levels of court in Ontario. He is recognized as a leading lawyer in various categories by Lexpert, Benchmark and Acritas, and is designated by the Law Society of Ontario as a Certified Specialist in Civil Litigation.