A good example of the careful distinctions which must be made in defining a legal term is found in Daniel Webster’s famous argument in the White Murder Case, of which an extract will be found below.  The question here is just how far the term “murder” shall be extended.

There are two sorts of murder; the distinction between them it is of essential importance to bear in mind:  (1) murder in an affray, or upon sudden and unexpected provocation; (2) murder secretly, with a deliberate, predetermined intention to commit the crime.  Under the first class, the question usually is, whether the offense he murder or manslaughter, in the person who commits the deed.  Under the second class, it is often a question whether others than he who actually did the deed were present, aiding and assisting therein.  Offenses of this kind ordinarily happen when there is nobody present except those who go on the same design.  If a riot should happen in the court-house, and one should kill another, this may be murder, or it may not, according to the intention with which it was done; which is always matter of fact, to be collected from the circumstances at the time.  But in secret murders, premeditated and determined on, there can be no doubt of the murderous intention; there can be no doubt if a person be present, knowing a murder is to be done, of his concurring in the act.  His being there is a proof of his intent to aid and abet; else, why is he there?

It has been contended, that proof must be given that the person accused did actually afford aid, did lend a hand in the murder itself; and without this proof, although he may be near by, he may be presumed to be there for an innocent purpose; he may have crept silently there to hear the news, or from mere curiosity to see what was going on.  Preposterous, absurd!  Such an idea shocks all common sense.  A man is found to be a conspirator to commit a murder; he has planned it; he has assisted in arranging the time, the place, and the means; and he is found in the place, and at the time, and yet it is suggested that he might have been there, not for cooperation and concurrence, but from curiosity!  Such an argument deserves no answer.  It would be difficult to give it one, in decorous terms.  Is it not to be taken for granted, that a man seeks to accomplish his own purposes?  When he has planned a murder, and is present at its execution, is he there to forward or to thwart his own design?  Is he there to assist, or there to prevent?  But “curiosity”!  He may be there from mere “curiosity”!  Curiosity to witness the success of the execution of his own plan of murder!  The very walls of a court-house ought not to stand, the plowshare should run through the ground it stands on, where such an argument could find toleration.