Why is the Constitution amended so rarely?
The US constitution was written by the Founding Fathers years ago but it could be adapted to suit the modern era by the amendment process however there have been just 27 amendments passed with a mere 17 in the last 210 years.
The first and probably most significant reason is that the Founding Fathers deliberately made the amendment process difficult. There is a formal process for amending the constitution which involves proposal and ratification. When an amendment to the constitution is proposed, it must be passed by both houses of the Congress by a two-thirds majority. Then it goes on to be passed by either the legislatures or conventions in the states, where it must be ratified by ¾ (38 states) of them. A second method (never used) is to get 2/3 of the legislatures of the states to call for a constitutional convention at which one or more amendments are proposed. If passed, any and all amendments from this convention would then have to be passed by 3/4 of the state legislatures or conventions again.
The convention method has never been used to propose an amendment. It has been used to ratify one, which was the 21st Amendment, repealing the 18th Amendment, which was national prohibition. This process has seen many proposals fall short of been passed as laws as even proposals which lose by just a single vote are not passed such as the 1995 balanced budget proposal which lost out in the senate.
Another reason for rare amendment is that the Founding Fathers created a document that was, at least in parts, deliberately unspecific. Most laws in the Constitution are non-specific and were not written to apply to the age of the Founding Fathers so can apply to the modern day.
The Supreme Court has the power of judicial review which allows it to interpret the Constitution and thereby in effect, change the meaning of words