9th Amendment. Logically, life must exist before any other rights can be exercised. Therefore, it must be protected to allow the option to exercise other said rights.
Back when the drug war threads were hot and heavy the 9th was always brought up. It was found that there had been only one case EVER decided by the USSC with the 9th as its basis. That was something about sexual relations or something. Even Bork stated that he never knew what the 9th amendment meant or why in the hell it was put there.