by the Circuit Court: this doctrine formed one of the grounds of objection, distinctly stated in the argument of the former case in this Court, and was distinctly noticed by the Court: and with this part of the opinion below, and the objection to it, distinctly in view, this Court decided this patent on this same specification to be valid, notwithstanding its want of a discrimination in terms between the improvement and the original invention; which was an express decision on this point, in favour of the plaintiff in error. He referred to various parts of the report of the former case of Evans v. Eaton, to support these positons; remarking, that although the Court certainly was not bound absolutely by its own decisions, and ought to overrule them, when satisfied of their incorrectness; yet they were the great landmarks of the law, and ought not to be overturned or shaken, without the strongest and clearest reasons.

a

The learned counsel also cited the authorities cited in the margin, as to the objection to the charge of the Court below, upon the ground that it had invaded the proper province of the jury, in respect to the sufficiency of the specification, and to the nature of the patentee's invention, as an improvement or an original discovery."

1822.

Evans

V.

Eaton.

Mr. Justice STORY delivered the opinion of the March 20th. Court.

This is the same case which was formerly before

a 3 Wheat. Rep. 454.

b 12 H. Bl. 478. 484. 497. 8 T. R. 99. 101. 103. 1 Gallis. 481. 1 Mason, 189. 191.

1822.

Evans

VS.

Eaton.

this Court, and is reported in 3 Wheat. Rep. 454. and by a reference to that report, the form of the patent, the nature of the action, and the subsequent proceedings, will fully appear. The cause now comes before us upon a writ of error to the judgment of the Circuit Court, rendered upon the new trial, had in pursuance of the maudate of this Court.

Upon the new trial several exceptions were taken in the question, by the counsel for the plaintiff. The first was to the

An interest

or a liability to

a similar action, admission of a Mr. Frederick, as a witness for the or standing in

the same pre defendant. It is to be observed, that the sole con

dicament with

the party, will

not render a troversy between the parties at the new trial was,

witness incom

ground of interest.

petent on the Whether the plaintiff was entitled to recover for an alleged breach of his patent by the defendant in using the improved Hopperboy. Frederick, in his examination on the voir dire, denied that he had any interest in the cause, or that he was bound to contribute to the expenses of it. He said he had not a Hopperboy in his mill at present, it being then in Court; that it was in his mill about three weeks ago, when he gave it to a person to bring down to Philadelphia; and that his Hopperboy spreads and turns the meal, cools it some, dries it, and gathers it to the bolting chest. Upon this evidence the plaintiff's counsel contended that Frederick was not a competent witness, but the objection was overruled by the Court. It does not appear from this examination whether the Hopperboy used by Frederick was that improved by the plaintiff, or not; but assuming it was, we are of opinion that the witness was

rightly admitted. It is perfectly clear, that a per-
son having an interest only in the question, and not
in the event of the suit, is a competent witness; and
in general the liability of a witness to a like action,
or his standing in the same predicament with the
party sued, if the verdict cannot be given in evidence
for or against him, is an interest in the question, and
does not exclude him. If nothing had been in con-
troversy in this case, as to the validity of the patent
itself, and the general issue only had been pleaded, the
present objection would have fallen within the gene-
ral rule. But the special notice in this case asserts
matter, which if true, and found specially by the
jury, might authorize the Court to adjudge the pa-
tent void, and it is supposed that this constitutes such
an interest in Frederick in the event of the cause,
that he is thereby rendered incompetent. But in
this respect, Frederick stands in the same situation
as every other person in the community. If the pa-
tent is declared void, the invention may be used by
the whole community, and all persons may be said
to have an interest in making it public property. But
this results from a general principle of law, that a
party can take nothing by a void patent;
and so
as such an interest goes, we think it is to the credit
and not to the competency of the witness. It is
clear that the verdict in this case, if given for Evans,
would not be evidence in a suit against Frederick,
but Frederick would be entitled to contest every
step in the cause, in the same manner as if no
such suit had existed. Non constat, that Frederick
himself will ever be sued by the plaintiff, or that if

far

1822.

Evans

V.

Eaton.

1822.

Evans

V.

Eaton.

of the State

sanction the

sued, any recovery can be had against him, even if the plaintiff's patent should not be avoided in this suit. It therefore rests in remote contingencies, whether Frederick will, under any circumstances, have an interest in the event of this suit, and the law adjudges the party incompetent only when he has a certain, and not a contingent interest. It has been the inclination of Courts of law in modern times, generally, to lean against exceptions to testimony. This is a case which may be considered somewhat anomalous; and we think it safest to admit The practice the testimony, leaving its credibility to the jury. Courts cannot Another exception was to the refusal of the admission of Court to allow a deposition to be read by the plainUnited tiff, which had been taken according to a prevalent are not taken practice of the State Courts. It is not pretended the laws of the that the deposition was admissible according to the positive rules of law, or the rules of the Circuit Court; and it is not now produced, so that we can see what were the circumstances under which it was taken. No practice, however convenient, can give validity to depositions which are not taken according to law, or the rules of the Circuit Court, unless the parties expressly waive the objection, or, by previous consent, agree to have them taken and made evidence. This objection, therefore, may at once Inconvenient be dismissed.

depositions in

the Courts of

the

States, which

according

to

United States,

and the rules

of their Courts.

and unnecessary practice of spreading the judge's charge

the record.

The principal arguments, however, at the bar have in extenso upon been urged against the charge given by the Circuit Court in summing up the cause to the jury. The charge is spread in extenso upon the record, a practice which is unnecessary and inconvenient, and may give rise to minute criticisms and observations

upon points incidentally introduced, for purposes of argument or illustration, and by no means essential to the merits of the cause. In causes of this nature we think the substance only of the charge is to be examined; and if it appears, upon the whole, that the law was justly expounded to the jury, general expressions, which may need and would receive qualification, if they were the direct point in judgment, are to be understood in such restricted

sense.

It has been already stated, that the whole controversy at the trial turned upon the use of the plaintiff's Hopperboy; and no other of the inventions, included in his patent, was asserted or supposed to be pirated by the defendant.

The plaintiff, with a view to the maintenance of his suit, contended, that his patent, so far as respected the Hopperboy, had a double aspect. 1. That it was to be as a patent for the whole of the improved Hopperboy, that is, of the whole machine as his own invention. 2. That if not susceptible of this construction, it was for an improvement upon the Hopperboy, and he was entitled to recover against the defendant for using his improvement. The defendant admitted that he used the improved Hopperboy, and put his defence upon two grounds: 1. That if the patent was for the whole machine, i. e. the improved Hopperboy, the plaintiff was not the inventor of the improved Hopperboy so patented; 2. That if the patent was for an improvement only upon the Hopperboy, the specification did not describe the nature and extent of the improvement;

1822.

Evans

V.

Eaton.