Which nation rejected the treaty of versailles, negotiating its own peace agreement with germany in 1921?

The United States rejected the Treaty of Versailles and negotiated its own peace agreement or agreement to end the war with Germany in 1921. The Senate would not vote to pass the Treaty of Versailles and instead sought to create a treaty or agreement solely based upon American terms. 

They made a checks and balance system to equal power within the branches. the "check" meant that one branch would watch one branch and "balance" them if they were too powerful. if you want more info on this, i would just google checks and balance system.