Means-Plus-Function Claims

In December 2009, the USPTO issued 16,000+ utility patents.  I used a software program to tally those patents that include claims with means-plus-function (MPF) claim language by looking for the terms “means for” or “means of” in the claims.

Only about 15% of the issued patent included at least one claim having an MPF limitation. Of patents that include an MPF limitation, half recite fewer than five such limitations. It appears that attorneys are using MPF claim language primarily as a back-up.  Longer claim-sets are more likely to include means-plus function language.  Thus 21% of patents with above-average-sized claimsets (by character count) include a means-plus-function limitation while only 11% of patents with below-average-sized claimsets include an MPF limitation. 

Looking claim-by-claim, I found that only 3% of the patents in my sample included means-plus-function limitations in every independent claim.

Means-plus-function terms are also also associated with non-assigned patents (usually individual inventors).  23% of non-assigned patents included an MPF limitation compared with 14% of assigned patents.

Patents arising from certain countries are much more likely to include MPF limitations. The chart below looks at the most common foreign filing jurisdiction for priority claims and reports the percentage of US patents arising from those foreign filings that include MPF limitations. 

PatentLawPic862

Means-plus-function claiming is primarily focused outside of the chemical and biotech art units. Thus, only 2% of patents examined in TC1600 (Biotech & Organic Chemistry) and 7% of patents examined in TC1700 (Chemical & Materials Engineering) include MPF limitations. The remaining technology centers averaged over 18% of patents including MPF limitations.

The chart below shows means-plus function claim prevalence of the top-20 patent owners (based on the number of patents owned in the sample). These companies are all primarily focused on electronics and are all headquartered in either the US or East Asia.

PatentLawPic863

The final chart shows the change in patent prosecution practice over time. Clearly, the use of means-plus-function claims has dropped over time. This is true even in the face of rising claim counts. The chart below is based on a sample of 22,000 randomly selected patents that issued 1976–2009.  I grouped the patents according to their decade of issuance and calculated the percentage that included at least one means-plus-function limitation.  *The chart also includes the December-2009 data mentioned above.

PatentLawPic865

Notes: My search is likely both over and under inclusive.  Although a claimed element that uses the terms “means for” is usually interpreted as an MPF claim, it is not always so interpreted. Likewise claim terms written in functional language without any structure in the claims can be interpreted as means plus function even if the absence of the “means for” language. Also, “step for” language is typically when a method step is functionally claimed.

35 thoughts on “Means-Plus-Function Claims

  1. 35

    “That’s half of the art of patent prosecution.”

    …in Mooney’s world that is. In Mooney’s sick world, there are also clandestine Examiner Interviewers waiting around every corner to conduct back alley interviews WITH NO TRANSCRIPT!!! And then there are those greed grubbers who actually try to assert patents FOR MONEY!!! They actually make money!!!

  2. 34

    “you can do better BigGuy”

    I can, but I won’t in this particular situation. Like I said, interference practice is too arcane for me, and patenthawk’s summary convinces me that there’s nothing earth-shattering in the case, despite Max’s swooning.

    Have a nice weekend.

  3. 33

    “but not the case itself” – you can do better BigGuy.

    MaxDrei, would it make your head spin faster to learnthat the copying is often dictated by the Office on close calls?

  4. 32

    “You can’t have “interference” without such “copying” can you?”

    Interference is a peculiar thing, which leaves many practitioners reeling. I turn interference issues over to a specialist, as the practice is too arcane for me. However, I don’t think there are any big theoretical flaws, just some procedural nuances that can get complicated.

    Yes, you have to have “copying”, but it doesn’t necessarily have to be literal copying, even if it often is. The point is that an interference proceeding is to settle interferences between claimed subject matter, not any disclosed subject matter. The Board here appears to have rightly understood that the same claim language could mean different things in two different applications. Procedurally, you need to figure out what claim 1 in application A means, in light of application A’s spec, and then determine whether that claim scope is the same or substantially the same as claim 1 in application B, read in light of application B’s specification. In the Philips case, it appears that Philips’ attorneys tried to confuse the Board with regards to the first step.

  5. 31

    I’m still reeling, regardless of the details. It’s because of the principle that a claim only makes sense as an indivisible part of a document in which it is the complement of the specification.

    What leaves me reeling is the notion of “copying” one claim, but not its complementary written description, into an alien patent, with totally different terminology and definitions sections.

    You can’t have “interference” without such “copying” can you?

  6. 30

    “Am I wrong?”

    I think so. I read the Patent Prospector summary, but not the case itself. As I understood it, the Board rejected the idea that one application’s claims could be read in light of the other application’s definitions. The District Court agreed with the board. The CAFC reversed the District Court on procedural grounds unrelated to this issue. No need for reeling.

  7. 29

    Thanks for the question Big. Have you yet read Philips v Cardiac CAFC 209-1241? Could it be that I have misunderstood it. I thought the BPAI and the DC was looking at a copied claim in the light of the specification of the case into which the claim had been copied. Am I wrong?

  8. 27

    gee, Malcolm, aka Jaime, I don’t know. Maybe your words at 6:33 PM and the start of the thread idea as I captured in my post at 7:06 PM, perhaps.

    Office training concerning “context” must be a black-hole and is no match for the shield of persistent ignorance.

  9. 26

    Troll: Malcolm, you have moved from a straight drafting question to a amending around that bad art question

    No, I haven’t. What makes you say that?

  10. 25

    Agree with you on double patenting Dude. But why pick out that one. How about the idea of “copying” a claim from one specification into another one with which it interferes. You would think that by now the Rules for settling an Interference are well-settled, but if you want something truly mind-boggling, just look at the Patent Prospector thread on the recent Philips (netherlands) interference case.

    Me, I thought you could only construe a claim in the light of the specification of which it is a part and which provides the “written description” that supports the claim and gives it sense and context.

    But, apparently not. I’m still reeling.

  11. 24

    I totally agree with you Max:as an EP Atty i love this rule 54(3).But it is nevertheless still foreign to 99.999% of US PAs.Similarly US law on double patenting issue is still a mystery for most of ROW PAs.

  12. 23

    Thanks Dude, for the info on the qualifying exam in France ato become a patent attorney.

    I have had some success with Art 54(3). Try this:

    Obviousness is needed, to stop people getting patents that cover that which is obvious over the universe of the published prior art. That’s all you need, right?

    Not quite. Obviousness doesn’t deal with the problem of the other guy, equally inventive, who just happened to file the day before you did.

    Shall you both get a patent. Or neither of you?

    How about giving him his patent, and you get a patent for everything you’ve got, that’s still NOVEL over the content of his filing, the day before.

    That’s why we need the novelty provision of Art 54(3). And it’s fair to both you and him. And it’s simple for the PTO and the courts. And it has turned out over the last 30 years over at least 40 countries that it works just fine.

    Which is why the whole of Asia uses it too. Right?

  13. 22

    More straw from Malcolm

    Compare “…always get around that bad art by adding a functional limitation to your claims”

    with

    “Side note: I’m relatively new to this game, but does drafting a structural claim based on functional language really help? If you’re defining the invention by it’s functionality why not just stick to method claims? Posted by: pickles | Jan 07, 2010 at 11:11 AM”

    Malcolm, you have moved from a straight drafting question to a amending around that bad art question. I know that it is difficult to put your examiner tricks aside, but try answering the question without so much twisted straw. It appears that “in context” is not something taught to vocal examiners who love to post under shields of persistent ignorance.

  14. 21

    irst of all to answer Max question;
    to become a French PA you must go through an exam including a lot of questions relating to US Patent Law (and japanese law).
    (and i would appreciate of course that the us patent bar include even only one question about french or ep patent law!!).
    Regarding the lack of grasping certain foreign rules remember also that europeans do not have the exclusivity: art 54.3 exists since 1973 in the Munich Convention and there is still to-day not one US PA who is able to understand this rule.
    NOW folks, if you trust Denis statistics, CISCO’s attorneys are almost twice as worse as frenchies in terms of drafting MPF claims;and HP PAs are not better than french PAs and worst than german!!What a shame!! could you explain that mister “7” or mister “former american” with your terrific experience and simple approach of these issues?May be they hired too many french PAs!
    Or is there any other possible reasons?
    Think macfly!think!

  15. 20

    Noise, the thing about case law is that it changes all the time. And as I’ve been trying to learn you for these past several years, it’s not changing in a direction which allows Applicants to play more games with claim language.

    Go ahead. Tell your clients that you can always get around that bad art by adding a functional limitation to your claims. I don’t care.

  16. 19

    “The answer is “in theory, no” but occasionally practitioners manage to slip something by a lazy or ignorant Examiner. That’s half of the art of patent prosecution.”

    pickle, please understand that your very very first lesson is that you cannot trust ANYTHING that Malcolm or 6 post on these boards. In fact, the one who posts as 6 was actually banished from another patent blog for his stupidity.

    Malcolm,
    Care to explain the case law and secondary sources (such as Chisum) that run counter to your “In theory, no” answer?

  17. 18

    In the electrical art it is often completely insignificant to the invention whether a particular block is implemented by vaccuum tubes, transistors, an IC or a computer algorithm. Unfortunately, US patent law deals with this particular fact of life extremely badly. In an ideal world, MPF claiming would come to the rescue, but in the US this particular solution to the problem has been rendered more or less useless.

  18. 17

    pickle says

    “True, it’s rare that they say “means for”, but is “processor for” or “thresholder for” really different? ”

    That does not sound like language for *method claims*. Isn’t that wording usually found in the apparatus or device claims rather than in the method claims?

  19. 16

    I’m relatively new to this game, but does drafting a structural claim based on functional language really help?

    The answer is “in theory, no” but occasionally practitioners manage to slip something by a lazy or ignorant Examiner. That’s half of the art of patent prosecution.

  20. 15

    “As Hal Wegner noted in 2004, “The warning bell sounded 10 [now 19] years ago …”

    Nine years have passed since 2004? That explains a lot…

  21. 14

    As Hal Wegner noted in 2004, “The warning bell sounded 10 [now 19] years ago about the dangers of “means” claiming in the twin en banc pronouncements in In re Donaldson Co., 16 F.3d 1189 (Fed.Cir.1994)(Rich, J. (en banc);[and] In re Alappat, 33 F.3d 1526 (Fed.Cir.1994)(Rich, J.)(en banc).”

    The remarkably slow acceptance of some important patent litigation case law as needing changes in application preparation and prosecution is less surprising considering the total absence of any PTO MCLE requirements for agent or attorney PTO practitioners, plus the isolated independent worlds in which these two branches of patent practice often operate.

  22. 13

    “I’m relatively new to this game, but does drafting a structural claim based on functional language really help? If you’re defining the invention by it’s functionality why not just stick to method claims?”

    The short answer – different (direct) infringers.

  23. 12

    observation: sometimes MPF language is needed because non-mpf language is rejected as being “intended use”

    The examiner’s pulling a fast one on ya there. Ignoring limitations based on their “intended use” is usually limited to interpreting the preamble. If the body of the claim is interpreted that way, just saying “means for [intended use]” isn’t going to help.

    Just Visiting: “How often does “means” language show up in software and/or computer-implemented method claims, I wonder?”
    Practically never. Did you intend to ask about method claims?

    Actually, I don’t think I’ve seen a software or computer implemented method claim NOT written in MPF language. True, it’s rare that they say “means for”, but is “processor for” or “thresholder for” really different? It looks like the courts are moving towards the stance that there is no difference.

    I can understand the US has some weird laws when compared to the rest of the world, and I’m willing to excuse foreign cases that don’t follow 112 6th, but I don’t see any legitimate excuse for a US case to use “means for” language and not provide structure in the spec. These laws have been around a while, and they’re not hard to understand. If you say “means for” in a claim and the spec doesn’t say “the means for include…” you have failed in your duty.

    Side note:
    I’m relatively new to this game, but does drafting a structural claim based on functional language really help? If you’re defining the invention by it’s functionality why not just stick to method claims?

  24. 11

    A loooong time ago, there were omnibus claims: “A turboencabulator substantially as shown and described,” to sweep up the details if no other claims survived. After 60 years, they’re back; but we call them means-plus-function.

  25. 10

    Lurker, are you referring to the notorious London Times newspaper headline “Fog in the Channel: Europe cut off”?

    No knowledge of non-European patent law is needed, to qualify as a European Patent Attorney. But it is needed, to qualify as a national patent attorney in Germany or in the UK.

    Then there is the factor you mention: that the British and German professions have between them got the US and JP workflow pretty much stitched up, the Brits because of the law they share with the US, the Germans because of the patent law they share with JP.

  26. 9

    Max,
    Critics on the European Patent Channel, France is isolated ;)
    The answer to the absolute numbers are the history of who is Patenting in Europe
    (Germany), the location of the EPO, and the Language (UK works for the US + later Japanese corporations)
    I had a look at the same EQE statistics, I recall the success rate by nationality was not the worst for the French candidates. Not in a way to explain the MPF differences.

  27. 8

    7: look at the statistics of who qualifies as European Patent Attorneys, out of the 3000 or so candidates from 36 Member States, who sit the tough qualifying exam each year. About 400 individuals satisfy the Examiners. Most of them come from Germany and the UK. I know why.

    Any attorney who has qualified as an EPA by examination is competent at drafting. Beware the ones who are “grandfathered” onto the Register of European Patent Attorneys, without having passed the qualifying examination. The biggest proportion of grandfathers on the Register are in those of the 36 Member States who have joined the European Patent Organisation most recently. Mind you, France has been in from the beginning.

  28. 7

    Max,

    I deal with a bunch of french, italian, german, and uk originated cases and I can tell you that the french are the worst, by far. Very low quality work, mpf language galore with NO actual structure discloses in the spec, etc.

    The best are the german and uk cases.

  29. 6

    Max, based on anecdotal data (working with French P.A.’s), the FR seems to unfortunately have P.A.’s with a particular difficulty grasping patent claims.

  30. 5

    Dennis writes:

    “It appears that attorneys are using MPF claim language primarily as a back-up”

    Who wouldn’t? The natural language of M+F gives broader scope of protection than anything else.

    Then there’s the point that only in the USA does M+F have any meaning other than its natural meaning. Will this unique American statutory provision, that complicates patent law so much and so unnecessarily, endure longer than the lifetime of the patent? Probably but, these days, who knows.

    In your Tables, dennis, France stands out. Is France a country in which patent attorneys have a particular difficulty to grasp that patent law abroad might be different than at home? I wonder: how much knowledge of foreign patent law does one need, in France, to qualify by examination as a patent attorney?

  31. 4

    “How often does “means” language show up in software and/or computer-implemented method claims, I wonder?”

    Practically never. Did you intend to ask about method claims?

  32. 3

    sometimes MPF language is needed because non-mpf language is rejected as being “intended use”

  33. 2

    Means-plus-function claiming is primarily focused outside of the chemical and biotech art units. Thus, only 2% of patents examined in TC1600 (Biotech & Organic Chemistry) and 7% of patents examined in TC1700 (Chemical & Materials Engineering) include MPF limitations.

    Note that there’s no legal explanation for why practitioners in the 1600 and 1700 art units do not rely on MPF claims to the extent that other art units do. It’s more a matter of tradition and also, perhaps, the fact that nearly all inventions in these art units are reduced to practice in one or more embodiments and these embodiments are likely to be the focus of a set of relatively narrow claims issuing over a number of applications.

    How often does “means” language show up in software and/or computer-implemented method claims, I wonder?

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