By 'decide the fate of' you mean, 'protect the lives of', right?
Yes, the gov't protects the lives of people. Or, is supposed to anyway. You have read the Declaration of Independence, have you not? Why do you think governments are formed among men, anyway?
What does the Declaration of Independence (Which by the way IS NOT THE LAW OF THE LAND) have to do with when life support is pulled from terminal patients? And yes Terri was deemed terminal because she was in a PVS. Happens dozens of times each week in America.