You only have to look at the abortion law. Introduced in 1967, the only conditions for terminating a pregnancy were if the baby was not likely to survive, or there would be "substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously handicapped", if giving birth would put the mother in danger, or if the result of the baby would lead to the mother being in so much emotional trauma that she could bring harm to the baby. That translates today as that if you want an abortion, you can get one. I think that if a euthanasia law was introduced, that's the same "slippery slope" would be inevitable, from noble and justified reasons, to ignoble and reasons driven by greed and immoral reasons.
I guess I would have to agree with the majority. It should be considered on a case by case basis. But, I also think we need to euthanize child molesters, rapist, murderers and drug dealers. Do I think that because Johnny and Becky broke up, they should be allowed to be euthanized? No. They can take care of that themselves. Have a great day!
Voluntary Euthanasia can be argued to be about human choice. If I was in pain I would want to be able to make life decisions for myself. Having this alternative does not mean that we will eventually have a situation where doctors are euthanizing unwitting patients. In fact I think it could decrease medical costs and increase quality of life.
Voluntary euthanasia would not be a slippery slope to involuntary euthanasia because strict standards must be in place to ensure a person is really beyond help. It would be obvious to any doctor if someone was being euthanized who might actually recover and regain some sort of functional life. As long as it's regulated in order to avoid this abuse, it should be a legitimate form of mercy.