Why might the court's interpretation of a certain amendment or civil liberty change over time?

Civil liberties are the restraints on government found in the Bill of Rights and the "Due Process" Clause of the 14th Amendment Civil liberties are primarily concerned with individual freedoms The Bill of Rights might have been more appropriately called the Bill of Liberties. While the seven articles of the Constitution express what the government /can/ do, the ten amendments contained in the Bill of Rights express what the government /cannot/ do.

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.