Deeply, deeply flawed analogy.
There is no state that permits one person to kill another for personal advantage or on a whim.
States may quibble over the exact circumstances that constitute legitimate self-defense, but no state permits anyone to justify a murder by saying: "I didn't like him being around so I killed him."
One could also argue over abortion whether or not an abortionist was in a culpable state of mind, whether or not the pregnancy constituted a direct threat to the mother's life, etc. just as the legal ramifications of all other killings are debated in court and classified into murder, manslaughter, negligent homicide, justifiable homicide, etc.
But it is an enormous jump from debating the merits of particular cases to asserting a carte blanche "right" to murder unborn children.
I do not believe there is a "right" to murder unborn children. But I also don't believe that the federal government has any right to impose its views on abortion on the states without a Constitutional Amendment. If New York wants to maintain legalized abortion, the federal goverment has no right to force them to prohibit abortion.
"But it is an enormous jump from debating the merits of particular cases to asserting a carte blanche "right" to murder unborn children."
Ah, but while virtually anybody you ask would consider shooting a clerk to death during a robbery murder, there's a fair percentage of people who do NOT consider an abortion, particularly in the early weeks, murder at all. So you either have to convince these people that it IS murder, or you have to convince enough legislators to say it's murder no matter what others believe.