Over the past decade, Arab constitutional courts dealt with a number of politically divisive questions in a context of crisis and conflict. They ruled on unconstitutional changes of government, governments’ competing claims for legitimacy, and issues of constitution-making. This paper examines three landmark cases from Egypt, Libya and Mauritania: The Egyptian Supreme Constitutional Court’s approach toward the military coup of 2013; The Libyan Supreme Court Constitutional Chamber’s ruling dissolving the elected parliament in November 2014 which paved the way for competing claims for legitimacy by two rival governments; The Mauritanian conseil constitutional rulings on the military coup of August 2008. While examining these cases the paper elaborates on the factors that determined the courts’ activism or self-restraint; their interpretive methods; implications of the courts’ rulings; and issues of enforcement and compliance. In concluding, the paper draws some tentative conclusions and lessons for the future of constitutional justice in the respective countries.