Catharine specializes in sex equality issues under international and constitutional law. She pioneered the legal claim for sexual harassment and, with Andrea Dworkin, created ordinances recognizing pornography as a civil rights violation. The Supreme Court of Canada largely accepted her approaches to equality, pornography, and hate speech. Her scholarly books include Sex Equality (2001) and Are Women Human? (2006). She is one of the most widely-cited legal scholars in English.