Means-plus-function ("MPF") claims define an element, in a combination claim, by its function instead of its structure. Under 35 U.S.C. §112(f), the statute reads:
An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
MPF claims are often thought of as narrow because they are limited to the corresponding structure, materials, or acts described in the specification. That characterization may be due to the use of MPF claims in mechanical inventions. MPF claims in the life sciences may in fact be broad. That is because the statutory term "equivalents thereof" does not reference the doctrine of equivalents, but rather refers to literal equivalents of structure, material, or acts that perform the same function. By writing life science claims in MPF format, the scope should literally encompass alternatives that provide the same function as claimed that correspond to the structure, material, or acts described in the specification.
An example of issued biotech MPF claims may be seen in U.S. 8,940,508:
14. A method of producing biomass or at least one free fatty acid or fatty acid derivative, the method comprising:
culturing a cyanobacterium that comprises a disrupted NPQ process in a suitable culture medium as an actively mixed culture in a pond or bioreactor that includes at least one active mixing device,
wherein the cyanobacterium experiences intermittent light conditions as a result of movement between brighter and darker regions of the pond or bioreactor, and
wherein the NPQ process is disrupted by a means for disrupting production of at least one carotenoid and/or a means for reducing expression of at least one carotenoid binding protein, and
further wherein disruption of the NPQ process does not include attenuating the expression of a light harvesting chlorophyll binding protein; and
isolating biomass or at least one free fatty acid or fatty acid derivative from the actively mixed culture,
wherein the amount of biomas or the amount of at least one free fatty acid or fatty derivative produced by the actively mixed culture is at least 20% greater than the amount of biomass or the amount of at least one free fatty acid or fatty acid derivative produced by a control culture,
wherein the control culture is identical to the actively mixed culture in all material respects except that the control culture cyanobacterium does not have a disrupted NPQ process.
15. The method of claim 14, wherein the means for disrupting production of at least one carotenoid targets a crtO gene or a crtR gene, and/or wherein the means for reducing expression of at least one carotenoid binding protein targets an ocp gene.
16. The method of claim 14, wherein the means for disrupting production of at least one carotenoid and/or wherein the means for reducing expression of at least one carotenoid binding protein is homologous recombination.
17. The method of claim 16, wherein the means for disrupting production of at least one carotenoid targets a crtO gene or a crtR gene, and/or wherein the means for reducing expression of at least one carotenoid binding protein targets an ocp gene.
As seen in the '508 claim 14, the drafter recited a combination of steps in a process. During prosecution, examiners will apply 35 U.S.C. §112(f) to a claim limitation if it meets the following 3-prong analysis:
1—Claim limitation uses terms: "means" or "step" or equivalent terms;
2—Such term is modified with functional language, typically linked to transitional language, such as "for"; and
3—Such term is not modified by sufficient structure, material or acts for performing the claimed function.
M.P.E.P. §2181(I). An example of an issued pharma claim in MPF format is found in U.S. 6,974,595:
Claim 34. A method for obtaining an average Tmaxof diclofenac in a human patient between 5 and 30 minutes after administration comprising orally administering a diclofenac formulation to said patient, wherein said diclofenac formulation comprises diclofenac in acid and/or salt form and means for enhancing said average Tmaxof said diclofenac, and wherein said diclofenac formulation is selected from: [a] and [b].
This claim was litigated and ended in a judgment and permanent injunction. See Nautilus Neurosciences, Inc. v. Wockhardt USA LLC., Case 2:11-cv-1997.
There are also examples of chemical MPF claims in the USPTO training materials, https://www.uspto.gov/sites/default/files/documents/112f_laundry.pdf
Takeaway
Overall, MPF language can be a powerful tool and an additional claim format in drafting pharmaceutical claims to encompass broader claim scope and thus more fully protect an inventor's rights and provide greater protection against infringement.
If you use MPF claiming, draft the specification to cover all the embodiments that you want to cover with this language (e.g., alternatives) and in the specification clearly link the "means for" function in your claim to the to the structure(s), materials or acts described in your specification.
Without that linking, your claim may be vulnerable to an allegation of written description and/or indefiniteness.1
Footnotes
1 For previous blog posts on MPF claiming in life sciences, see https://www.finnegan.com/en/insights/blogs/prosecution-first/an-issued-life-science-mpf-u.s.-patent-claim-ex-parte-gleave.html and https://www.finnegan.com/en/insights/blogs/prosecution-first/got-pharmaceutical-means-plus-function-claims.html
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