After 9/11, the United States and its allies took measures to protect their citizens from future terrorist attacks. While these measures aim to increase security, they have often been criticized for violating human rights. But violating rights is difficult in a constitutional democracy with separated powers and checks and balances. This paper empirically investigates the effect of the post-9/11 terror threat on human rights. We find strong evidence of a systematic increase in rights violations in the U.S. and its ally countries after 9/11. When testing the importance of checks and balances, we find that this increase is significantly smaller in countries with independent judicial review (counter-majoritarian checks), but did not depend on the presence of veto players in the legislative branch (majoritarian checks). These findings have important implications for constitutional debates on rights protection in times of emergency.