Can An Article V Convention "Runaway" And Rewrite The Constitution?

No, the answer is no.

There's a lot of talk about new Constitutional amendments, for a variety of reasons. Republicans and Conservatives are interested in amendments to require a balanced budget and limit terms in Congress, and Democrats are interested in repealing the First Amendment. So, clearly, the Right is worried about a convention that is hi-jacked to repeal protections of important rights.

But the worry is misplaced. Here is the text of Article V:

The Congress, whenever two thirds of both houses shall deem it necessary, shall propose amendments to this Constitution, or, on the application of the legislatures of two thirds of the several states, shall call a convention for proposing amendments, which, in either case, shall be valid to all intents and purposes, as part of this Constitution, when ratified by the legislatures of three fourths of the several states, or by conventions in three fourths thereof, as the one or the other mode of ratification may be proposed by the Congress; provided that no amendment which may be made prior to the year one thousand eight hundred and eight shall in any manner affect the first and fourth clauses in the ninth section of the first article; and that no state, without its consent, shall be deprived of its equal suffrage in the Senate.

Pretty straight-forward, despite being a brick. Here it is a little cleaner:

The Congress, whenever two thirds of both houses shall deem it necessary, shall propose amendments to this Constitution, or, on the application of the legislatures of two thirds of the several states, shall call a convention for proposing amendments,

which, in either case, shall be valid to all intents and purposes, as part of this Constitution, when ratified by the legislatures of three fourths of the several states, or by conventions in three fourths thereof, as the one or the other mode of ratification may be proposed by the Congress;

provided that no amendment which may be made prior to the year one thousand eight hundred and eight shall in any manner affect the first and fourth clauses in the ninth section of the first article; and that no state, without its consent, shall be deprived of its equal suffrage in the Senate.

So first, there's nothing in Article V that suggests a state cannot limit it's convention call to a specific purpose, or withdraw it's support if the convention goes rogue. But let's presume it cannot be limited or withdrawn.

It doesn't matter.

A Convention can be called by two-thirds (66%) of the States, or two-thirds of both houses of Congress. But whatever comes out of the Convention is not automatically part of the Constitution. In order for the proposed amendments to become part of the Constitution, it would require three-fourths (75%) of either State legislatures or State conventions to implement the proposed amendment.

That means that any convention that goes rogue or becomes "runaway" would run right into the wall of ratification. If just thirteen States refuse to sign onto the amendments, they don't become Amendments. And the very definition of a "runaway convention" is one where the proposed amendments are anathema to a large portion of the country, so it would fail by definition.

And besides, the fear that a Constitutional Convention would produce an unwanted result could apply to any attempt at proposing amendment at any time. That cowardice should not prevent us from taking necessary steps, especially given the sheer impossibility of a runaway convention actually being successful.

It only takes thirteen States to kill an amendment. One-third of one-percent of the total US population could kill an amendment. Pretending a renegade convention could do any harm is just absurd.