The first case the Supreme Court is hearing this session is whether Oregon's assisted suicide law should be allowed to stand. The Bush administration opposes it on the grounds that the federal government has final authority on how controlled substances can be used and since federal legislation prohibits the use of drugs to help people end their lives, state laws allowing doctors to prescribe lethal doses of these substances should be struck down.
There are several questions raised by this case: Is it wise to have doctors assisting people in killing themselves? If doctors should not do this why do we have doctors assist the state in executing condemned prisoners? Will allowing the state to help people die erode the value we place on life? These are all important questions, but I'm not sure that they're relevant to the Supreme Court's ultimate decision. The narrow issue is whether it is unconstitutional for the state of Oregon to allow doctors to prescribe lethal dosages of drugs when federal law forbids it. The wider issue is whether the states have the right under the constitution to permit their citizens to take their own lives under certain circumstances.
It seems that there is really only one way a conservative can consistently answer this latter question and that is to say that the states should indeed have that right. This is ultimately a state's rights matter, just like conservatives say abortion should be. It would be very difficult to argue, as conservatives do, that whether their citizens should have the right to kill their unborn children should be left to the voters of each state to decide, but that whether their citizens will have the right to kill themselves must not be left to the voters of the states.
This is not to say that laws permitting self-euthanasia, or assisted self-euthanasia, are wise or moral. It's simply to say that the decision as to whether such practices should be legally condoned should be left to the citizens of the state in the same manner conservatives believe laws on abortion should be. How it can be argued that euthanasia is a matter for the federal government to control but that Roe v. Wade should be overturned and abortion laws thrown back into the lap of state legislatures is not very clear, at least not to me.