George mason was one of the most vocal critics of the constitution and his protests are considered a major factor in the drafting of the bill of rights. why was he so concerned about the absence of a bill of rights in the constitution?

Worried about overreaching power of the federal government. 

George Mason supported the Articles of Confederation and thought a federal government would endanger individual rights granted by nature. He rallied in Virginia against ratification because he believed it would destroy the rights of the states and the people. Actions like his led to the passage of the Bill of Rights.