How did checks and balances guard against tyranny?

One of the things that worried the Founding Fathers most was what kind of government to have-- and they knew they did NOT want a monarchy. So, when the American colonies won their independence from England, the goal was to set up a government that would never have a king, or an autocratic ruler who could do whatever he wanted. The system of checks and balances established three branches of the government, each with its own unique role. The president was the head of the executive branch; congress, which could make the laws, was the legislative branch; and the Supreme Court was the judicial branch.

The system was designed to keep any one branch of the government from becoming too powerful: each one was in some way separate from the others, yet each branch was also interdependent. For example, the president could promote or champion a policy, but it was congress that was tasked with turning policies into laws; and the Supreme Court could overturn a law that was not constitutional. And while, over the years, there have been times when this system did not function in an ideal way (the Supreme Court validated laws about racial segregation, for example), for the most part, the checks and balances have indeed kept any of the branches from taking over, and have also kept our presidents from having unchecked power.