The first revolution toppled tsar rule and put a provisional government had little support,
This situation make it possible for the Bolsheviks second revolution to bring down the government. When the civil war was over, the Bolsheviks now replaced the tsar and hold the majority of control in the government. They later on replaced the officials that ruled under the tsar with their own, and implemented communist principle to Russian economy.
One branch of government can check the other through the usage of "Checks and Balances", which states that no one branch can become to powerful, as the others have the right to suppress the other branch's power.
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Special words or expressions that are used by a particular profession and are difficult for others to understand are called "jargon," since they are often only understood by people "in the know".
The Bill of Rights is the historical document that upholds these important principles.