there is a conflict between the law and its application. It
is the human element in the administration of the law that
enables lawyers to get a living. It is usually not difficult
to tell what the law is; the puzzle is how it is going to be
applied in any individual case. How it is going to be applied
depends very largely upon the practical side of the matter and
the exigencies of existing conditions.

It is pretty hard to apply inflexibly laws over a hundred
years old. It is equally hard to police a city of a million
or so polyglot inhabitants with a due regard to their
theoretic constitutional rights. But suppose in addition that
these theoretic rights are entirely theoretic and fly in the
face of the laws of nature, experience, and common sense?
What then? What is a police commissioner to do who has either
got to make an illegal arrest or let a crook get away, who
must violate the rights of men illegally detained by
outrageously "mugging" them or egregiously fail to have a
record of the professional criminals in his bailiwick? He
does just what all of us do under similar conditions--he
"takes a chance." But in the case of the police the thing is
so necessary that there ceases practically to be any "chance"
about it. They have got to prevent crime and arrest
criminals. If they fail they are out of a job, and others
more capable or less scrupulous take their places. The
fundamental law qualifying all systems is that of necessity.
You can't let professional crooks carry off a voter's
silverware simply because the voter, being asleep, is unable
instantly to demonstrate beyond a reasonable doubt that his
silver has been stolen. You can't permit burglars to drag