In 2012, the Supreme Court of Canada ruled that people with HIV are legally obligated to disclose their serostatus before sex with a “realistic possibility” of HIV transmission, suggesting a legal obligation to disclose unless they use condoms and have a low HIV viral load (< 1500 copies/mL). We measured prevalence and correlates of ruling awareness among 1230 women with HIV enrolled in a community-based cohort study (2015–2017). While 899 (73%) participants had ruling awareness, only 37% were both aware of and understood ruling components. Among 899 aware participants, 34% had never discussed disclosure and the law with healthcare providers, despite only 5% being unwilling to do this. Detectable/unknown HIV viral load, lack of awareness of prevention benefits of antiretroviral therapy, education ≤ high-school and high HIV-related stigma were negatively associated with ruling awareness. Discussions around disclosure and the law in community and healthcare settings are warranted to support women with HIV.