If executing a human being is ever humane, a firing squad is a reasonable
way to do it. It is quick and relatively painless, and often done in the open
air to give the criminal a last glimpse of the sun. One of its best features
is that it frees the executioners from unbearable guilt. Traditionally, one of
the rifles used by a firing squad is left empty, so that ever after, each rifleman
can tell himself he did not kill.
A firing squad is more humane than some methods of killing people. It is generally quick, and likely a lot less painful than electrocution or a gas chamber. Also, it is a more humane method in that no one really knows which person fired the deadly bullet. This takes some stress off of the people doing it.