According to Justice Bertha Wilson, there is "overwhelming evidence that gender-based stereotypes are deeply embedded in the attitudes of many male judges" and that "gender difference has been a significant factor in judicial decision-making". Unfortunately, Justice Wilson's observation has been subjected to few empirical tests. At the same time, scholarship suggests that in other contexts (e.g., legislatures), the presence of a "critical mass" of women may be necessary before substantive gender based differences emerge. It is important to know whether these gender differences do exist and whether they only appear after a "critical mass" of women have been appointed because an implicit premise in the argument for affirmative diversification in elite appointments is that gender matters substantively. We seek to explore the validity of these assumptions by analyzing the votes of judges in the Supreme Court and the provincial appellate courts of Canada. Canada provides an ideal setting to explore these questions because since the early 1980s female representation on appellate courts has gone from virtually non-existent to 44% on the Supreme Court and over 50% on some appellate courts. We propose to test whether there are gendered patterns of voting, and if so, whether such patterns appear only after a critical mass is reached, using a logistic regression model of the differences in the voting behavior of male versus female justices, using the universe of Supreme Court votes from 1982 through 2007 and a sample of the votes of judges on the provincial courts of appeal. Our analysis then comes to the conclusion that supports previous research into gendered voting; namely that women vote more liberally on civil rights and equality as well as private economic cases, and more conservatively on criminal cases. However, we find no evidence that indicates a need for women judges and justices to be accompanied by other female colleagues for them to vote sincerely.