How is the 2nd Amendment be parsed?
A well regulated Militia being necessary to the security of a free State, the right of the people to keep and bear Arms shall not be infringed.
Here's a similar structure:
"A well-schooled electorate, being necessary to the security of a free State, the right of the people to keep and read Books, shall not be infringed."
"A well-schooled electorate" is a nominative absolute.
"being necessary to the security of a free State" is a participial phrase modifying "electorate".
The subject (a compound subject) of the sentence is "the right of the people".
"shall not be infringed" is a verb phrase, with "not" as an adverb modifying the verb phrase "shall be infringed".
"to keep and read books" is an infinitive phrase modifying "right".
Source: http:/www.mcsm.org/english.html