The judges had no basis for making any judgment for the medical experimentation that took place in the Nazi war camps unless they set down some rules to judge by.

The family needs to know whether they want to be on a ventilator or not. Discuss those issues with your friends, your family, with anyone who is likely to have significant input when the time comes. Don't leave it to the courts to designate your proxy.

Justice is the hardest precept for the individual physician to deal with. It asks how to best allocate resources fairly so that patients with similar situations get treated the same way.

If a person has a quality of life and an expectation for improving that are both by all evidence, by all consensus negligible, is there a general right to life?

I don't think there's any question in ethical thinking that if treatment is medically futile, you don't continue it. But what is 'medically futile?' Often there's no clear line.

It's the patient's expression of their values.

Every treatment can potentially have an adverse effect. Everybody knows even two aspirins for a headache has a bad effect for someone somewhere. On balance, positive effects have to outweigh the negative.