Fixing the 2nd amendment

2a

Nothing in the Bill of Rights has caused more debate, in recent times, than the second amendment.  As written, it seems that there are no limits placed on private citizens.  Others would argue that the words imply a well regulated militia.  Retired Justice John Paul Stevens suggests that adding 5 words to the current amendment would remove all ambiguity.  What do you think?

“A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms when serving in the Militia shall not be infringed.”

Your opinion please.  Why can’t states regulate guns?  The Bill of Rights defines the limitations of the federal government, not the States.