There is NOTHING any government can prevent someone from doing, including commit suicide by their own hand, assuming they are able.
One can murder, one can do drugs, one can rape, but they do NOT have a right to do so in our society or under the Constitution.
The Bill of Rights are titled "amendments" meaning they are not simply an addendum to the Constitution, but amendments to it. In many cases the Bill of Rights amendments clarify or qualify other portions of the Constitution. The Second Amendment, taken in its whole, states what is "necessary to the security of a free state". That is relevant to and tied to the Preamble (purpose) of the Constitution where "the common defense" is clearly mentioned as something to be constituted by the described government and powers given to them.
The thing that is described as "being necessary to the security of a free state" (the common defense) is "a well-regulated Militia", NOT, a right to keep and bear arms. Militia is also clearly referred to in the powers of the legislature in Article I, Section 8.
If the 2nd Amendment was intended to be unattached from and unrelated to Militia and intended to protect a "right" for any and all of "the people" to keep and bear arms, any arms, any mention of Militia would be unecessary and all that would be needed would be to state, "The right of the people to keep and bear arms shall not be infringed" or, the right of the people to keep any and all arms for their personal defense, shall not be infringed. What more would be needed?
On the other hand, if a goverment enacts law that requires all citizens (at the time that included ONLY, free white men) to not only enroll in and train with others in and as a "well regulated Militia" and to furnish their own arms, it would be easily rendered dysfunctional if those "people" could be banned from keeping and bearing arms. In the context of "a well regulated Militia" the thing described in the 2nd Amendment as "being necessary to the security of a free state" (federal or one of the individual states of the united ones) (a common defense) "the people" are those engaged in what is necessary to the security of a free state. In the context of a "well regulated Militia in 1792, that was ALL able bodied citizens (free white men) between the ages of....In the context of a 2013 "well regulated Militia" NOT ALL able bodied citizens are included as "the people" who are engaged in legal duty to the "security of a free state", but there are "the people" who are in service and duty to "the common defense" of one of the 50 states of the United [50] States.
Any person in the world is free to defend themselves. In this nation, in order to protect the rights of people killed or injured by those claiming self defense, "self defense" is not simply a claim one makes, but an action that must be proven to be self-defense for what should be obvious reasons. If they are not obvious enough for some, imagine being invited over for dinner by a neighbor who you have run into some conflict with. They tell you they want to bury the hatchet and express that to you by having you over for a meal. Unbeknownst to you, they are in fact, luring you over to get you out of their hair. Their plan? Have you for dinner, ply you with some drinks, show you their gun collection, let you handle one of their guns, go back to the table, have some more drinks, then begin to piss you off by reverting back to the aggressive neighbor they have always been. You don't pull a gun on them, but you are heard raising your voice in return to their raised voices. Next thing you know, you've been shot and you don't remember anything after that, because you're dead. They claimed "self defense" and that you brandished a gun, the gun your fingerprints were all over. Without further investigation who is to know their claim is not true. Further investigation shows they were lyng, thus, whether a "stand your ground" law is in place or not, there is a responsibility to prove any claim of self-defense, not to protect "bad guys", but to protect innocent people.