Why is the separation of govt. powers a requirement for a society to be free?

To prevent on branch of government from getting to strong, and allowing for another part of the government to check the work of an other, this is known as checks and balances. 

The majority of both parties voted in favor of the bill all senate republicans voted in favor of the bill

More than 4 million enslaved hunan beings in the south and they touched every aspect of the regions social, political and economic life.