Double Patenting when you have a Common Assignee but No Common Inventors

This is a bit of an in-the-weeds question, even for Patently-O.

Because firms tend to operate within a certain market area and use a particular technological approach, it makes sense that a patentee may well create prior art that blocks future innovations. One solution offered by the law is the “common owner ship excption.”  In particular, the statutory definitions of prior art include the ‘common owner exception’ that excludes a right-owner’s prior-filed patent applications from the scope of prior art for later-filed applications so long as those prior applications were not published by the filing date of the later applications.

AIA Expansion of Exception: This is one area where the AIA reduced the scope of prior art. Namely, before the AIA the common owner exception excluded the prior applications only with regard to obviousness consideration (assuming different inventors). The AIA expands the exception to also exclude these prior-applications from anticipation consideration.  With this expansion, we might expect some increase in double patenting problems.

Double Patenting Common Assignee but No Common Inventors: My question relates to the statements in MPEP 804 that examiners should issue double-patenting rejections when two commonly-owned inventions claim the same subject matter even when there is no overlapping inventorship:

Claims in commonly owned applications of different inventive entities may be rejected on the ground of double patenting. This is in accordance with existing case law and prevents an organization from obtaining two or more patents with different expiration dates covering nearly identical subject matter. See In re Zickendraht, 319 F.2d 225, 138 USPQ 22 (CCPA 1963) (the doctrine is well established that claims in different applications need be more than merely different in form or content and that patentable distinction must exist to entitle applicants to a second patent) and In re Christensen, 330 F.2d 652 (CCPA 1964). . . .

[A rejection is proper even when] the reference … and the pending application are … by a different inventive entity and are commonly assigned even though there is no common inventor.


The problem with the MPEP here is that the cases cited are not on-point – i.e., they do not say anything about whether a double patenting rejection may persist when there are no inventors in common.  We know that statutory-double patenting is said to stem from 35 U.S.C. 101 and, likewise, we learned in AbbVie v. Kennedy Institute that obviousness-type-double-patenting also finds its roots in Section 101.  The problem with that approach is that Section 101 remains old-school and still focuses on “inventors” rather than applicants or owners.

My Question: What is the legal source of the MPEP’s declaration that a double patenting rejection is proper based upon common-ownership even when the two documents have no common inventor?  I suspect that there is a case on this, but I don’t know. 

21 thoughts on “Double Patenting when you have a Common Assignee but No Common Inventors

  1. 8

    I personally think that the doctrine that the second to issue patent covering the same invention is invalid — unless the first is removed in an interference — is a good one.

    1. 8.1

      It wasn’t that long ago that I was personally involved in a case where we were being approached by a major company with a patent that claimed the same invention as claimed in another patent that had issued first. Both were filed within 3 months of each other. Had the law at that time been clear that the second-to-issue patent was invalid or at least unenforceable over the first-to-issue absent an interference, it would have made my life a lot simpler.

      Anyhow, there is a Supreme Court case on the point that the first-filed but later-issued patent is invalid over a second-filed but earlier-issued patent. I wonder how the Federal Circuit is going to deal with that case?

      Oh! That’s right. The Federal Circuit really doesn’t care about Supreme Court authority, and never has. Witness the recent case about laches. It’s their trademark after all.

    1. 7.1

      Dear Professor Crouch,

      Yes there is. The author discusses that scenario in the section dealing with joint research.


  2. 6

    Dear Professor Crouch,

    Emerson Stringham, Double Patenting. Pacot Publications (Washington D.C. 1933) is a good source; he has a whole section on your question. You may want to take his cited cases and then shepardize them. There are quite a few of them. Some are even Riding Circuit cases. I hope this is helpful.


  3. 5

    Dennis, consider In re Longi, relevant part quoted below:

    Appellants also maintain that the entire doctrine of double patenting of the obviousness type should not apply to commonly-owned applications with different inventive entities. A rejection based upon such a doctrine, appellants say, is unduly restrictive and discourages group research. Moreover, each inventor in a research department should be entitled to separate patents for his or her own independent contribution to the basic objective of the overall research project. Such a broad position has been previously rejected, and it is inconsistent with both our precedents and recent legislation.

    Many times our predecessor court, the Court of Customs and Patent Appeals, has treated commonly-owned applications by different inventors as though they were filed by the same inventor, and then relied upon the doctrine of double patenting of the obviousness type to deny a second patent on subject matter not patentably distinct from the claims of the first patent. In fact, the appellant in In re Rogers, [394 F.2d 566, 157 USPQ 569 (1968)] made an argument similar to the one the present appellant makes here. In that case, Rogers asserted that the obviousness type double patenting rejection was “distressing” to corporate practitioners and did not take into account the considerable exchange of information between inventors. The result, as the argument goes, would be that a corporation would find itself in a [894] “box” because patent protection for both inventions would not be possible.

    As we declared in that case, appellants, and those in like situations, are not in an inescapable “box.” A patent may still issue if an applicant faced with such a rejection were to file a terminal disclaimer under 35 U.S.C. § 253, disclaiming “any terminal part of the term … of the patent,” thereby guaranteeing that the second patent would expire at the same time as the first patent. It is well-established that a common assignee is entitled to proceed with a terminal disclaimer to overcome a rejection based on double patenting of the obviousness type. Since the second patent would expire simultaneously with the first, this use of a terminal disclaimer is consistent with the policy that the public should be free to use the invention as well as any obvious modifications at the end of the patent’s term.

    In re Longi, 759 F.2d 887, 893-94, 225 USPQ 645 (Fed. Cir. 1985) (citations omitted – affirming rejection for obviousness-type double patenting of chemical claims of over an issued patent commonly owned by the assignee of the application, even though the inventive entities between the application and issued patent were different, where the claims of the application were obvious in view of the claims of the issued patent and four prior art references because the claims of the application recited a nitrogen-containing titanium compound as a component of the claimed catalyst, the prior issued patent recited a non-nitrogen-containing titanium compound as a component of the catalyst, and the prior art taught that the nitrogen-containing titanium compound could be substituted for the non-nitrogen-containing titanium compound, and the applicant’s evidence of secondary consideration of unexpected results was deficient)

      1. 5.1.1

        Dennis, but it does beg the question of why two patents with different inventors would be invalid — there is no statutory basis for it. Neither is there a basis in any law about extending term because assignees are not inventors.

        If faced with a recalcitrant PTO, I wonder how they would react if one assigned the referenced patents to a different entity. I would like to see the PTO and the courts deal with that one.

        This is why I think the law will develop that if such an assignment is made, the first filed will become prior art to the second filed.


          Ned, I have not read these yet, but they may offer some explanation:

          (1) Gholz, The Law of Double Patenting in the CCPA, IV APLA Quarterly Journal No. 4 (1976) at 273, “Authority for Double Patenting Rejections”

          (2) Witherspoon, So-Called Common Assignee Double Patenting – An Issue in Search for a Home, IV APLA Quarterly Journal No. 4 (1976) at 329.


            Dennis, I read the Chico Goltz article, and the cases he sites all go back to Miller v. Eagle Mfg. Co., 151 U.S. 186, 14 S. Ct. 310, 38 L. Ed. 121 (1894). link to

            “The result of the foregoing and other authorities is that no patent can issue for an invention actually covered by a former patent, especially to the same patentee, although the terms of the claims may differ; that the second patent, although containing a broader claim, more generical in its character than the specific claims contained in the prior patent, is also void; but that where the second patent covers matter described in the prior patent, essentially distinct and separable from the invention covered thereby and claims made thereunder, its validity may be sustained.

            In the last class of cases it must distinctly appear that the invention covered by the later patent was a separate invention, distinctly different and independent from that covered by the first patent; in other words, it must be something substantially different from that comprehended in the first patent. It must consist in something more than a mere distinction of the breadth or scope of the claims of each patent. If the case comes within the first or second of the above classes, the second patent is absolutely void.”

            Of course, the Chico Goltz article also notes that a terminal disclaimer cannot be used when the two patents are claiming the same invention. The second-to-issue patent is void. Suffolk Co. v. Hayden, 70 US 315 – Supreme Court 1866 link to

            This presents some difficulty for Gilead, in that according to the Supreme Court, if the second-to-issue patent is claiming the same invention, it is void and according to all case law, no terminal disclaimer is possible. This is not a matter of policy and extension of term. It is a matter of 101 in that there can only be one patent on an invention. It makes no difference who the inventor is.

  4. 4

    Dennis, you and I both know in England there could not be two patents on the same invention, and a writ scire facias was available to the first patentee to have the second patent declared invalid. The writ was enacted into law in 1790, in Section 5, and in Section 10 of the Patent Act of 1793. See, ex parte Wood & Brundage. One of the grounds for revocation was that “the patentee was not the first true inventor or discoverer.”

    101 existed in these early statutes in the virtually the same form and words as today’s statute. The writ scire facias was repealed, however, in 1836 and replaced by a defense to infringement, that was then incorporate as 102(g) in 1952.

    With the repeal of 102(g), there is no statutory basis remaining for denying an independent inventor a patent on the same invention other than the rules on first to file. Thus, if two independent inventors file on the same date, they are both legally entitled to receive a patent. These two patents do not become invalid if later they are assigned to the same entity.

    The exclusion of prior art based on common assignment removed the remaining statutory basis for not granting two patents on the same invention to independent inventors when assigned to the same company. However, I would argue, that the law should develop that if they cease to be commonly owned, the second-filed should be invalid over the first filed.

    1. 4.1

      The point about 101 being present in the early statutes should be emphasized, as the initial congresses did not seem to believe that it was sufficient to prevent issuing a patent on the same invention to two different inventors.

    2. 4.2

      Thanks Ned. Do we have precedent to support your notion that “if two independent inventors file on the same date, they are both legally entitled to receive a patent.” The Supreme Court might be willing to say no to both on double patenting grounds.

      1. 4.2.1

        Well, Dennis, we do know that Bell won his interference by filing earlier in the same day as his rival.

        The Supreme Court never has had to face this issue given Section 5 of the 1790 Act and Section 10 of the 1793 Act. If push came to shove, the Court might simply restore first to invent as the solution to the conundrum with the idea that there can only be one patent on an invention and the solution offered by the first congresses was the right one. Alternatively, they may simply say that a terminal disclaimer requiring continued common ownership was implied in the removal of the prior art status because the basic patent law since the days of England would not tolerate two patents on the same invention.

  5. 3

    Response to your question professor:
    In re van Ornum, 686 F.2d 937, 942-43 (CCPA 1982)(“ On the other hand, numerous cases were considered in which application claims were directed to mere obvious modifications of, or improvements on, inventions defined in the claims of patents already issued to the same inventors, or to common assignees, and it had been decided that they might be allowed to go to patent if the applicants filed terminal disclaimers. We classified these as ‘obviousness type double patenting.’”). The fact that CCPA distinguishes between “same inventors” from “common assignees” suggests that double patenting is appropriate for applications have no common inventor but having the same assignee.

    1. 3.1

      Thanks Richard. This is helpful, but I’m not convinced yet.

      Two issues. First, unfortunately the Van Ornum decision does not cite any of these “numerous cases” that have the same inventors. The suggestion that some cases did not have the “same inventors” is different from saying that there is no inventor in common. In particular, the “same inventor” term usually indicates identical set of inventors. There is an intermediate ground of overlapping inventors that the cases could be referring to here.

  6. 2

    Couldn’t it be based on 35 USC 152? Rights granted by 101 are assignable via section 152. Therefore the reference to “whoever” obtaining “a patent” refers to “whoever” holds those rights at the time the patent grants, here the common assignee.

  7. 1

    “The problem with the MPEP here is that the cases cited are not on-point…”

    That’s a problem with the MPEP a lot more than just “here.”

    1. 1.2

      And it might be frustrating to patent agent candidates who know what the law really is, but who are nevertheless bound by what the MPEP says it is.

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