"At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life" (Planned Parenthood v. Casey).
If all values are purely subjective, then your life is only worth what I hold it to be worth. And if I hold it to be worth less than anything else, and I further believe that it is worth sacrificing your life to achieve something I value more, then you have no right to stop me. To do so would be to impose your meaning of human life on me, and my right to define human life for myself is at the heart of liberty. What are you, a fascist?
"Then mankind would have become as the Great Old Ones; free and wild and beyond good and evil, with laws and morals thrown aside and all men shouting and killing and reveling in joy. Then the liberated Old Ones would teach them new ways to shout and kill and revel and enjoy themselves, and all the earth would flame with a holocaust of ecstasy and freedom" (H.P. Lovecraft, "The Call of Cthulhu").
Fhtagn, baby. The stars will soon be right. They must be. After all, we're almost there already.
Of course the best part of all thus bull plop is that it is self-refuting. If liberty means that I get to define life, the universe and everything, then that means I have every right to define them in such a way as to allow me to forcibly impose my definitions on others. Which in turn violates the right people have to define life, the universe and everything.
Do we actually pay Supreme Court justices? Because this is first year undergrad, intro to philosophy, "here's your F-" crap.