The times to kill are:

War. A sad but quite real fact of life.

Self-defense. Yet another sad but real fact of life.

Slaughter of animals for food. That includes licensed hunting and a regulated harvest of non-endangered game species.

Euthanasia of dumb animals who are near death and suffering, due toi illness or injury and are not likely to recover even if aggressively treated.

Euthanasia of persons who are likewise near natural death or death due to injuries if they, their next of kin, and attending physician, show proper cause why it is the humane thing to do.

Execution of violent criminals adjudged by a panel of experts (Jury) as "most likely to re-offend,"

And, persons who suffer such severe chronic psychiatric trauma that life is meaningless, painful, or otherwise so unsatisfying that they request humane death in a clinical setting.

That does NOT justify Obama's proposed "encouragement to end one's life past retirement age as a cost-saving measure."

http://en.wikipedia.org/wiki/Action_T4