Proposed amendment passes with 2/3 majority in senate and representatives or a national constitutional convention is called on an amendment by 2/3 of state legislators
State Level
An amendment is ratified by a simple majority in 3/4 of state legislatures or an amendment is ratified by state ratifying convention 3/4 of states
There have been 27 amendments, 10 in the bill of rights. Key examples include the 2nd amendment (right to bare arms), and 14th amendment (granted all people born or naturalised in the US the same rights under law), the 13th amendment ended slavery.
Advantages
+ Broad support
+ Prevents short lived trends becoming amendments
+ Protects constitution and its principles
+ Prevents tyranny of large states and single parties
+ Few changes
+ It works
+ Prevents abuse of power (G.W Bush had his proposal for line veto in 2006 rejected by congress)
Disadvantages
- There have been mistakes, such as 18th amendment (prohibition)
- Tyranny of minority
- Power given to Supreme Court e.g. Citizens United V FEC (2010)
- Ignorance of minority interests
- Outdated: Equal Rights Amendment 1982 wouldn't give equal rights to both sexes