Q.Why must a constitution place limitations on rulers? Can a constitution give no power at all to citizens?

Simply knowing who has the authority to make a society's rules is still not enough to guarantee a just or livable society, because that same authority could go on to pass laws that are plainly unjust — banning a particular religion, dictating what people may wear, forbidding certain songs, forcing one group to serve another without the right to own property, permitting arbitrary arrest, or restricting basic freedoms based on someone's caste or skin colour. Even if such laws were passed through an entirely legitimate procedure, they would still be obviously unfair. This is why constitutions place fundamental limits on what any government is allowed to impose on its own citizens — limits that the government itself may never cross, regardless of how it came to power. The most common technique constitutions use to do this is naming a set of fundamental rights that every citizen possesses: protection against arbitrary arrest, and basic civil liberties such as freedom of speech, freedom of conscience, freedom of association, and freedom to pursue a trade or bus …