For Montesquieu, despotism was one of the worst threats for a government. He pointed separation of powers as the best way to prevent it, in which legislative, executive and judicial power was excercised by different bodies of government, and these bodies were ruled by supreme law.
The system of checks and balancesis very important for the U.S. government, since it was developed to assure that neither of the government's branches would empower too much. The writers of the U.S. Constitution developed a system that divides power between legislative, executive and judicial, and incorporates several limits and controls on the powers of every branch.
My guess would be to try to save people from dying
Explanation
In the graph it shows an increase in dying between the 1960's. People would protest to help the population and to save people from more devastation and loss. They might also protest to save families from having to mourn over dead family members
