sentation or concealment, without fraudulent design, concludes the party making it as to the character and scope of the invention attempted to be covered by the patent. What has been properly described and claimed is regarded as its true subjectmatter; what has been voluntarily omitted or misstated is considered as abandoned to the public, or as permanently excluded from that particular patent; and though it may sometimes be made the subject-matter of a future patent, it cannot be incorporated into the existing patent by re-issue. An error which occurs through inadvertence, accident, or mistake, is neither intentional nor fraudulent, but is consistent with an honest attempt to describe and claim the complete invention, as the inventor has himself conceived it and rendered it available for public use. It is for the purpose of correcting this latter error only that an amendment by reissue is permitted.

express provisions of the statute. An attempt to deceive the public by a suppression of the truth or the suggestion of a falsehood in the description and specification of the patent is therein made a valid defence in any action based upon the patent. The right to amend a defective patent either by disclaimer or re-issue is also conditioned upon the absence of any fraudulent or deceptive intention on the part of the patentee. Diligence and good faith are alike required of him as qualities of conduct and purpose without which no concession of exclusive privileges to him can be allowed. See Miller v. Brass Co. (1882), 104 U. S. 350; 21 O. G. 201.

8 That a re-issue cannot claim matter intentionally omitted from the original, see Ex parte Mahnken (1887), 40 O. G. 915; Shirley v. Mayer (1885), 23 Blatch. 249; 25 Fed. Rep. 38; 34 O. G. 1391. 4 That "mistake" as ground for reissue is not the same thing as "misunderstanding," see Ex parte Wilkins (1883), 24 O. G. 1270.

That it is immaterial by what mistake or inadvertence a re-issue becomes necessary, see Stimpson v. Westchester

R. R. Co. (1846), 4 How. 380; 2 Robb, 335.

That the re-issue affords prima facie evidence of inadvertence, but may be overcome by other proof, see Odell v. Stout (1884), 22 Fed. Rep. 159; 29 O. G. 862.

That "inadvertence, etc.," exists in reference to the application, not the invention, and occurs only where the former does not describe and claim what the inventor intended to protect, see Ex parte Mahnken (1887), 41 O. G. 1269.

That a Claim left out of the original because the applicant did not consider its subject-matter patentable cannot be inserted in the re-issue, see Ex parte Mahnken (1887), 40 O. G. 915.

That an error in opinion or judgment is not "mistake or inadvertence," see Ex parte Mahnken (1887), 40 O. G.

915.

That a re-issue which was evidently procured to cover other later devices and not to cure faults arising from inadvertence or mistake is invalid, see New. ton v. Furst & Bradley Mfg. Co. (1886), 119 U. S. 373; 38 O. G. 104.

§ 686. Re-issue not Permitted where the Defects in the Original Patent Arose through Fraud.

With reference to this third proposition, defects and insufficiencies in the Description or Claims of a patent may thus be grouped in three classes: (1) Those which are intentional and fraudulent; (2) Those which are intentional but not fraudulent; (3) Those which are neither intentional nor fraudulent, but which arise from inadvertence, accident, or mistake. Concerning the first class, the law is plain and fully settled. The question as to the existence of a fraudulent and deceptive intention is a question of fact to be determined, upon direct or inferential evidence, by whatever tribunal may have jurisdiction of the controversy in which the question is raised. Thus on an application for a re-issue, the Commissioner may inquire into the original good faith of 'the patentee, and upon satisfactory proof of bad faith may deny the application. The courts, in ascertaining the validity of a re-issue already granted, may pursue the same investigation, and if a fraudulent intent appears to have been entertained by the original patentee, may treat the re-issue as invalid.1

§ 687. Re-issue not Permitted to Reject Matter Intentionally Inserted in the Original Patent, nor to Restore Matter Intentionally Excluded.

The line between the second and third classes, though sufficiently clear in statement, is not always easy to define in

§ 686. 1 The extent of the authority of the courts to inquire into the intention of the patentee in omitting or misstating any feature of the invention in his original patent cannot, at present, be precisely defined. That the decision of the Commissioner on the good faith of the patentee in applying for a reissue, and on the absence of corruption in allowing it, is final, except upon proceedings brought to repeal the re-issued patent, is conceded; and that a patent may be collaterally attacked, on the ground that its Description and Claims are fraudulent and intended to deceive, is beyond question. A disposition to II.-25

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enlarge the sphere of judicial authority, and permit the courts to go behind the finding of the Commissioner upon the questions of inadvertence, etc., in ordinary actions on the re-issued patent has recently been manifested; and though indulged with great caution, and with perhaps too much regard for the supposed prerogatives of the Commissioner, is so clearly in the interests of a just administration of the law that its result in bringing all these issues into the jurisdiction of the courts in any suit, in which the validity of the patent is involved, may be considered as already certain. See §§ 714, 715, and notes, post.

practice. That matter which has once been deliberately embraced within or excluded from a patent can neither be disclaimed nor reclaimed by an amendment, and that matter unintentionally included or omitted may be afterward rejected or inserted, are rules distinct, precise, and exhaustive. The difficulty is found in ascertaining whether the original misstatement was deliberate or unintentional, and in devising and applying tests by which this question may be settled without relying on the evidence of the inventor as to the object which he had in view. The positions generally taken by the Patent Office and the courts in reference to this question are in harmony with those assumed in regard to other aspects of the doctrines of abandonment and estoppel.1 Abandonment is always a question of intention, to be gathered in all cases from the conduct of the inventor toward his invention or the public. Estoppel rests upon an actual or presumed intention of the inventor, which is made effective by forbidding him to depart from the position he has once assumed. Errors occurring in the Description or Claims of the original patent are thus held to have been deliberate or unintentional according to the indications afforded by the circumstances causing, or connected with, or relating to the occurrence of these errors. Such circumstances may precede or be concurrent with or subsequent to the issue of the original patent. They may appear upon the face of the patent itself, or in the records of the Patent Office, or in the actions or omissions of the inventor; and whenever from these circumstances it is evident that the inventor deliberately made his attempt to describe and claim the invention in the form and with the limitations inserted in the original specification, any endeavor to correct the statement, by changing that form or discarding those limitations in the re-issue, is unlawful. What circumstances have been treated by the Patent Office or the courts as indicative of such intentional exclusion, will be now considered.

§ 687. That whenever it may be necessary for the protection of either public or private rights, the doctrine of estoppel, as now applied in courts of law and equity to ordinary trans

actions, will be resorted to in the adjudication of patent causes, see §§ 346 and notes, 357, note 3, 390 and notes, ante, and §§ 981, 1021, 1046, 1195, and notes, post.

§ 688. Re-issue not Permitted to Enlarge the Claims of the Original Patent by Including Matter once Intentionally Excluded.

It may be premised that this question rarely arises except in cases where the alleged error in the original patent consists in an undue restriction of its Claims.1 An amendment made in the Description, placing the invention more fully in the possession of the public and not enlarging the privileges of the inventor, is not subject to objection unless the original were fraudulent and the patent, therefore, void. An amendment merely limiting excessive Claims in the original patent is also rather for the public interest than that of the inventor, and when attempted without unreasonable delay seldom encounters opposition. But when the inventor endeavors by amendment to extend his Claims, and thus encroaches on a domain previously left open to the public or occupied by rival inventors, his efforts are naturally subjected to severe adverse criticism and his rights are properly confined within the narrowest limits. Hence it is in cases where the re-issue, though not materially altering the description of the original invention, claims for it essential features differing in number or in character from those claimed for it in the former patent, or where subordinate or dependent inventions, described but not claimed in the original patent, are claimed in the re-issue,

§ 688. 1 It is not, however, true that the right to a re-issue amending the Description or narrowing the Claims can be exercised without limitation. The patentee owes a duty to the public to present them with an accurate delineation of his invention, and to confine his Claims to the essential features which he has created; and he is open to the imputation of bad faith if he fails to amend his patent in these particulars when such amendment becomes evidently necessary. Thus even a disclaimer cannot save a patent unless made without un reasonable delay; and acquiescence in a faulty description may bar the allowance of a re-issue, if it does not furnish evidence of an original intention to de

ceive. Illustrations of these principles may be found in the following cases:

That while less delay is allowable in expanding Claims than in restricting them, no unreasonable delay as to either can be permitted, see Ex parte Matthews (1884), 26 O. G. 823.

That a defect in the Description may be cured by re-issue, even though the right to cure one in the Claim has been lost by delay, see Miller v. Brass Co. (1882), 104 U. S. 350; 21 O. G. 201.

That the original Claims may be reproduced in a re-issue without reference to delay, see Yale Lock Co. v. Sargent (1886), 117 U. S. 536; 35 O. G. 497; Steam Gauge Lantern Co. v. Miller (1882), 11 Fed. Rep. 718.

that the amendment is attacked, and that the question of deliberate or unintentional exclusion from the previous patent is involved.

§ 689. Intentional Exclusion Shown by Express Disclaimer in the Original Patent or during the Proceedings in the Patent Office.

A voluntary and intelligent disavowal of any matter which is embraced in the original description of the invention is conclusive evidence of its intentional exclusion from the patent. This disavowal may consist in an express disclaimer embodied in the specification, or filed subsequently