When ‘Interlock’ Causes Gridlock: Lessons from the Federal Circuit’s Decision in CoolIT Systems v. Vidal

by Dennis Crouch

In a nonprecedential decision, the Federal Circuit has vacated and remanded a PTAB decision siding against the patentee.  The key issue on appeal was the proper construction of the claim term “matingly engaged,” which appears in the limitation “a compliant member matingly engaged with the second side of the housing member.” CoolIT Sys., Inc. v. Vidal, No. 2022-1221 (Fed. Cir. Mar. 7, 2024). Coolit v Vidal.

One of the take-aways from the case is that parties should be cautious about using terms that may themselves require construction, as this can lead to a “construing the construction” problem. Courts aim to adopt constructions that clarify the meaning of the disputed term without introducing new ambiguities.   See Jason Rantanen, Construing Claim Constructions, Patently-O (Sept. 28, 2011, 4:13 PM).

CoolIT’s U.S. Patent No. 9,057,567 is directed to a heat exchange system designed to efficiently cool electronic devices. The system includes a heat sink with fins defining microchannels, a housing member with a recessed region on one side, and a compliant member that is “matingly engaged” with the recessed side of the housing and thus partially defines an opening over a groove in the heat sink.  Together, the compliant member and groove form an inlet manifold that distributes fluid to the microchannels. This configuration solves the problem of effectively conveying and distributing coolant to the microchannels in a direction transverse to the fins, and then in parallel through the microchannels, to optimize heat transfer. The “matingly engaged” limitation is key because it provides a mechanical connection that seals the fluid pathways without the need for welding or adhesives.

The ‘567 patent has two distinct priority claims. Along one line, the patent claims priority back to a 2007 provisional application (via continuation-in-part from a 2008 utility application).  The second line claims priority to a separate 2011 provisional filing.  The term “matingly engaged” first appeared in the 2011 provisional application to which the ‘567 patent claims priority, and CoolIT argues that the new additions in that provisional are distinct from the 2007 approach that shows an alternative connection method of fusing components together.  I think it is important to note that the Federal Circuit did not delve deeply into the complex priority claim or let it color its claim construction analysis. Instead, the court focused on construing the term “matingly engaged” based on the intrinsic and extrinsic evidence before it, without regard to the potential priority issue or any blame towards the patentee for creating this complex or confusing situation. This approach demonstrates the court’s commitment to an objective claim construction process that does not penalize patentees for claiming priority to multiple applications — or even for obtaining patents that lack some amount of clarity.

Back to the case: The Board more broadly construed “matingly engaged” to mean “fitted within” and did not distinguish between fused connections and unfused fitted connections.  With this broader construction, the Board found that the prior art reference (that seemingly contained fused components) taught the “matingly engaged” limitation.  On appeal, the Federal Circuit has vacated and remanded — finding the Board’s construction too broad – but, CoolIT did not get all that it asked-for.

On appeal, the Federal Circuit determined that “matingly engaged” requires the components to be “joined or fitted together” in some fashion, as the parties seemed to agree. However, the court found that “something more must also be included in the construction” beyond just joining or fitting together in order to give weight to both “matingly” and “engaged.”

CoolIT had proposed adding “interlock” to the construction. But the Federal Circuit had concerns that “interlock” could cause more confusion than clarity. The parties disagreed, for instance, on whether “interlock” required complementary contoured shapes or not. During oral arguments, Judge Byrson explained:

The word interlock is giving me trouble, frankly. Because it seems to me it’s one of those words which if you use it to construe another term, you still have to construe the term interlock. You really haven’t made a whole lot of progress, it seems to me.

Ultimately, the Federal Circuit concluded that the correct construction of “matingly engaged” should be “mechanically joined or fitted together.” The court found this captured the meaning of the term and the various arguments. It encompasses parts that are joined by overlapping or with complementary shapes, but is not limited only to those arrangements.

The court explained that the inclusion of “mechanically” properly excludes chemical bonding or fused connections, like sealing with glue/solder or welding to fuse into a single part, which CoolIT stressed were distinct from mating engagement. The patent itself also distinguishes between “sealingly engaged” (used in claim 28) and “matingly engaged” (used in claim 1).

It is interesting here that the PTAB’s original construction was different from that suggested by either party. Likewise, the CAFC’s decision has resulted in a construction not suggested by any party.  The fact that neither the PTAB nor the Federal Circuit wholly adopted either party’s proposed construction demonstrates the independence and critical role of the adjudicators in interpreting claim language. At the same time, it seems to highlight a problem with the limited proposals and suggestions often provided to tribunal.

Back to the case: Since the Board did not consider whether the prior art disclosed the “matingly engaged” limitation under the correct construction, the Federal Circuit vacated the Board’s decision and remanded for further consideration.

On remand, the Board will need to reevaluate whether the prior art discloses or suggests the “matingly engaged” limitation under the proper construction. The court’s opinion suggests that certain types of connections, like fusing/welding components together or intermediary sealing, would not qualify as mechanical joining/fitting. So the specific details of how the references disclose connecting the compliant member and housing will likely be key to the unpatentability analysis.

Judge Lourie wrote the opinion that was joined by Judges Bryson and Stark.

Reuben Chen of Cooley LLP argued the case for CoolIT and was joined on the brief by Heidi Keefe and Dustin Knight of Cooley LLP along with Lloyd Pollard of Workman Nydegger.  For the intervenor Dir. Vidal, Monica Barnes Lateef argued and was joined on the brief by Peter Ayers, Mai-Trang Dang, and Farheena Yasmeen Rasheed.

21 thoughts on “When ‘Interlock’ Causes Gridlock: Lessons from the Federal Circuit’s Decision in CoolIT Systems v. Vidal

  1. 6

    It seems to me that the plain meaning of “mate” requires that the mechanical connection be at least in-part due to the complimentary or the partly complimentary shapes of the two parts connected. For example, a clip or a clamp connects to all sorts of things of essentially arbitrary shapes, but one would not say that they connect as a result of “mating.” Perhaps “interlock” was not a great choice for claim construction, but it does seem like it was a step in the right direction (at least as far as the plain meaning of the term).

  2. 5

    Why is the Director intervening in an appeal to take back an issued patent? If the USPTO wants to increase participation and diversity of inventors who file for patents, they should stop taking the patents back.

    1. 5.1

      That’s always been a power of the Director.

      Perhaps a brighter realization that the Patent Office is within the political branch as an administrative agency (Executive Branch) could be made, and appropriate guardrails could be installed.

    2. 5.2

      Good point Josh. Perhaps all patents should come with an * on their covers.

      * Subject to revocation by the PTO at any time for any reason; depending on which way the wind is blowing.

      1. 5.2.1

        That was a view reflecting comments of mine to that late Ned Heller, but he refused to pursue my suggestions, and we instead got what we got in Oil States.

  3. 4

    Oh the joy of being a patent attorney, privileged to debate what is, in context, the meaning of “mating”. It strikes me that it implies temporality. Things that engage “matingly” tend afterwards to disengage (as opposed to being engaged without limit of term).

    And then, of course, as ever, size matters. Imagine two nominally flat surfaces (typically metal) urged to rub against each other so hard and fast that the resultant friction between their tiny surface rugosities causes them to fuse together (matingly engage, perhaps) permanently.

    Quite a challenge then, for the court to divine the accurate meaning of the term.

    The supreme court in England would be asking itself “What was the inventor using the language of the claim to mean, to the person skilled in the art”. What enquiry is fairer and more pragmatic than that, I ask? The answer seems obvious, at least to me.

    1. 4.1

      It strikes me that it implies termporality.

      Have you ever taken marriage vows (seriously taken them)?

      1. 4.1.1

        anon, you and I differ on what “mating” means. Do you have in mind that the congregation in a church wedding ceremony go there to watch the two protagonists “mating”? Even asking the question amuses me greatly.


          Mate as a noun is by which the ceremony is undertaken. It is in that context that the vows apply.

          Consummation is an altogether different aspect – on that point, your view of “temporality” indeed does apply.

          My context was not on the short aspect, but on the permanent aspect.

  4. 3

    Seems like the CAFC got it right here. Without reading the patent and prosecution histories of all the parent apps, it seems weird for the Board to settle on a definition that included non-mechanical joining.

  5. 2

    Dennis, would drafting 112 supportable substitute claims for this subject patent 9,057,567 of this CAFC remanded IPR make a good exam question? [Or would clarifying the disputed parts-attachment language actually make a significant 103 difference, as I gather will now have to be re-decided?]

    1. 2.1

      Paul – Who exactly


      any substitute claims in an IPR?

      1. 2.1.1

        Re: Who examines proposed substitute claims in an IPR? If they are of any infringement concern, the petitioner’s law firm and its resources. [Far more intensely, and better briefed for the PTAB, than a PTO ex parte application examiner would have the time or resources for].
        But the point was whether or not this mess was avoidable by different claim language someone could suggest?


          The point is that there is no actual examination.

          The petitioner is notan examiner, and there is no examination under the law by a designated Government employee from which a proper patent grant flows.


            IPR claim substitutions can only be entirely narrowing in claim scope. The IPR PTAB APJs are the designated government employees who must approve substitute claim entry and allowance over patents and publications cited by the opposing party, plus adequate 112 support [and they frequently do not so approve].


              That “can only be entirely narrowing in claim scope.” does not help you because the wider scope at original allowance was removed.

              The ONLY time that ‘narrowing’ helps you is in prior submitted claims that would ‘escape’ both the original art of record AND the new art from the petitioner – but this again would only be properly examined by

              you guessed it

              an examiner.

              NONE of the petitioner, the patent holder, nor the neutral tribunal are – or may – take up that role.


          Paul – do you see the (slight) bit of hypocrisy with your attempt to respond at post 1.1 and your error here at 2.1.1?


            What inconsistency? Whatever interpretation of an original or substitute claim the PTAB makes in an IPR can be rather easily changed by the Fed. Cir. in an appeal per Markman v. Westview Instruments, just as they did in this case, or by any D.C. Markman in litigation.


              The inconsistency of you wanting a certain level of “letter of the law,” at the same time refusing to see that the AIA’s “letter of the law” is

              You just keep on cheerleading.

  6. 1

    Nice to know you have to appeal to the Fed. Cir. before you can get an actual on the record “BRI” of your claim terms.

    1. 1.1

      Inevitable result of the Markman v. Westview Instruments (1996) unanimous decision of the Sup. Ct. that claim construction is a matter for the court [not unlike construing contract terms in that respect]. Or, to put it another way, this is not a fact finding for which the PTAB would get more respect on appeal under the APA.

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