Just a note on the U.S. constitution.  The reason why amendments are so difficult to change, is because the constitution outlines basic rights that SHOULD be difficult to alter or change. The right to free speech, freedom from search and seizure, free exercise of religion, right to bear arms etc. That is our federal constitution. However, each state is allowed to pass it's own laws that do not contradict the federal constitution. For example, the death penalty.  I believe 36 states have the death penalty. 14 dont. My state, New Jersey, just abolished it yesterday. So, state laws are relatively easy to change. Rights guaranteed in the constitution, not so.  This makes sense because every election the new party could change the constitution with a 51% vote.  This would make constitutional rights subject to the whim of every election.  

BTW: From my distant vantage point, the EU seems to be the rule of elites and bureaucrats.  If the net effect is to impose another layer of bureaucracy, taxation and regulation on european citizens, dont expect them to love the EU.

Terry