delivered the opinion of the court.
The defendants in error, as plaintiffs, sued the plaintiffs , in error, iu assumpsit in the Circuit Court, upon a special parol contract, purporting to have been made in 1844, to the effect that they having á patent for Sickles’s cut-off, for saving fuel in the-working of steam-engines, and-the -defendants being ;the owners of a certain steamboat, it was agreed between them that the said patentees should attach to the engine of the defendants one of their machines; and that the defendants should pay for the use thereof three-fourths of the saving of fuеl produced thereby, the payments tp be made from time, to time, when demanded. That, to ascertain the saving of fuel, an experiment should be made in the manner described jn the declaration, and that'the result should be taken as the rate -of saving during the continuance of the contract, which was to be as long as the patent'and the steamboat should last. The plaintiffs aver, that the experiment had been made, and the rate of saving had been duly ascertained; and that the machine had been used' in connection with the engine on the said boat, until the commencement of the suit.
In the first count of the declaration, the plaintiffs further stated,, that they bi’ought, in March, 1846, a suit on this con-' tract in the Circuit Court for the sum then due,, and had obtained a verdict and judgment therefor in the Circuit Court in 1856, and had thus established conclusively the contract be-' tween the parties. These last allegations are not contained in the.second count. The defendants pleaded the general issue.
The plaintiffs.produced upon the trial, as the only testimony Of the contract, the proceédings of the suit mentioned in the declaration, and insisted that these proceedings operated as an estoppel upon the defendants. These proceedings consisted of a writ, a. declaration, containing two counts upon the con-, tract, and the commоn counts, and the plea of the general issue; also a docket entry of a general'verdict, in favor of the plaintiffs, on the entire declaration, and a docket entry of judgment, subsequently rendered on the first count — a count similar to the counts in the declaration in the present suit. The defendants objected to these docket entries as- evidence
*341
.of a verdict and judgment; but insisted they were simply memoranda or minutes, from which a record of a verdict and judgment were to be made. It appears that in the courts Of this district, as in Marylаnd, the docket stands in the place of, or, perhaps,- is the record, and receives here all the consideration that is .yielded to the. formal record in other States. These -memorials of their proceedings must be intelligible to the court that preserves them, as their only evidence, and we cannot, therefore, refuse to them faith and credit. Bateler
v.
State, 8 G. and J., 381; Ruggles
v.
Alexander,
The Circuit Court adopted these conclusions of the plaintiffs, and excluded the testimony offered by the defendants, to prove those facts.
The authority of the
res judicata,
with the limitations under which it is admitted, is derived by us from the Roman law and the Canonists. Whether a judgment is to have authority as such in another proceeding, depends,
an idem corpus sit; quantitas eadem, idem jus ; et an eadem causa petendi et eadem conditio personarum; quae nisi omnia concurrent alia res esi;
or, as stated by another jurist,
exceptionem rei judicatoe, obstare quotiens eadem qcestio'inter easdern personas rcvocatur.
The essential conditions under which the exception of the
res judicata
becomes applicable are the identity of the thing demanded, the identity of
*342
the cause of the demand, and of the parties in the character in which they are litigants. This court described the rule in Apsden
v.
Nixon, (4 How. S. C. R., 467,) in such cases to be, that a judgment or decree set up as a bar by plea, or relied on as evidence by way of estoppel, must have been made by. a court of competent jurisdiction upon the same subject-matter, between the same parties for the same purpose. The thing demanded in the present suit is a sum of money, being а part of the consideration or price for the use of a valuable machine for which the plaintiffs had a patent, and is the complement of a whole, of which the sum demanded in the first count of the declaration in the former suit is the other part. The speсial counts in the declaration of each suit are similar, being framed upon this contact; and a decision in the one suit on those counts in favor of the plaintiffs necessarily included and virtually determined its sufficiency to sustain the title of the-plaintiffs' on it. It was, therefore, admissible as testimony. This conclusion is supported by adjudged cases, and the authority of writers on the law of evidence. Gardener
v.
Buckbe,
This presumption is a guаrantee of the future efficacy and binding operation of -the judgment. It presupposes' that all the constituents of the judgment shall be preserved by the court, which renders it in an authentic and unmistakable form. In the courts, upon the continent of Europe,, andln the courts of chancery and admiralty in. the United States' and: Great Britain, where the function-of adjudication.is performed entire by a tribunal composed of one or more judges, Ihis-has been done without much difficulty. The separate functions of the judge and jury, in common-law courts, crеated a.necessity for separating issues of law from'issues of fact; and with the increase of commerce and civilization, transactions have become. more complicated and numerous, ánd law and fact have become more closely interwоven, so as to render their separation more embarrassing. The ancient system of, plead- . ing, which was conducive to the-end of ascertaining' the material issue between the parties, and the preservation in a permanent form of the evidence of thе adjudication, has •been condemned as requiring uuuecessaiy precision, and subjecting parties to over-technical rulés, prolixity, and- éxpense. - A system of general pleading has been extensively adopted in this country, which rendered the application of- thе principle contended for by the plaintiffs impracticable, unless we. were prepared to restrict within narrow bounds the authority of the ves judicata. It was consequently decided that it was not neces *344 eary as between parties and privies that the i’ecord should show that the question upon -which the right of the plaintiff to recоver, or the validity of the defence, depended for it to operate conclusively; but only that the same matter in controversy might have been litigated, and that extrinsic evidence would be admitted to prove that the particular question was material, and was in fаct contested, and that it was referred to the decision of the jury.
In Young
v.
Black, 7 Cr., 565, this court admitted in evidence a record of a former' suit between the parties, in which judgment was rendered for the defendant, supported by parol proof that the cause of action in the two suits was the same.' The court say : “ The controversy had passed in
remjudicalam';
and the identity of the causes of action being once established, the law- would not suffer' them again to be drawn into question.” The current of American authority runs in the same direction. Wood
v.
Jackson,
. In the case before the court, the verdict was rendered upon two special counts, and the general counts in assumpsit, but the verdict iii the subsequent stage of the proceedings was applied by the court only to the first count. The record produced by the plaintiffs showed thаt the first suit was brought apparently upon the same contract as the second, and that the existence and validity of that contract might have been litigated: But the verdict might have been rendered upon the entire declaration, and without special reference to the first count. It was competent' to the defendants to show the state of facts that existed at the trial, with a view to ascertain what was the matter decided upon by the verdict of the jury. It may have been that there was no contest in reference to the fаirness of' the experiment, or to its sufficiency to ascertain the premium to be paid for the use'of the machine at the first trial, or it may have been that the plaintiffs abandoned' their special counts and recovered their verdiqt upon the general counts. . The judgment rendered- in that suit, while it remains in force, and for the purpose of maintaining its validity, is conclusive of all the
*345
facts properly pleaded by the plaintiffs. But when it is presented as testimony in another suit, the. inquiry is competent whether the' same issue has been tried and settled by it. Mеrriam
v.
Whittemore,