United States: Fed. Circ. Clarifies The Test For Patentable Subject Matter

Originally published by Law360

A recent Federal Circuit decision should bring hope to those discouraged by recent decisions invalidating patents for lacking patentable subject matter. The simplistic application by many district courts of the "laws of nature are unpatentable subject matter" test articulated by the U.S. Supreme Court in Mayo Collaborative Services v. Prometheus Labs., Inc., 132 S. Ct. 1289 (2012) may have led some to conclude that thousands of patents are at risk. However, comparing the claims held to be directed to an unpatentable law of nature in Ariosa Diagnostics Inc. v.  Sequenom  Inc., 788 F.3d 1371 (Fed. Cir. 2015), with claims that were deemed valid in Rapid Litigation Management Ltd. v. CellzDirect Inc., No. 2015-1570, 2016 WL 3606624 (Fed. Cir. July 5, 2016), may help to allay those fears, and may help practitioners write better claims and defend patents against attacks of invalidity.

Background: The Supreme Court's Mayo Test for Patentable Subject Matter

In Mayo, the Supreme Court confirmed that there is a natural phenomenon exception to patentable subject matter under 35 USC § 101. Under Mayo, if (1) patent claims are "directed to" a law of nature; then (2) they must be analyzed to determine whether the claim elements transform the claim into a patent-eligible application of that natural law. Ariosa, 788 F.3d at 1375, citing Mayo, 132 S.Ct. at 1297-98. Mayo step (2) involves what the Supreme Court characterized as a search for an "inventive concept," to determine whether the claims cover "significantly more" than an ineligible law of nature. Id. citing Mayo, 132 S.Ct. at 1294.

The Claims in Ariosa Diagnostics Were Held to Describe a Natural Phenomenon

The Federal Circuit's decision in Ariosa Diagnostics, regarding Pat. No. 6,258,540 (the '540 Patent) provides a useful illustration of claims the Federal Circuit considered to come under Mayo's proscription against patenting laws of nature. The inventors discovered that cell free fetal DNA (cffDNA) exists in a pregnant mother's blood stream. Therefore, dangerous conventional tests that breached the amniotic sac were not needed to collect fetal DNA.

Claim 1 of the '540 Patent reads as follows:

1. A method for detecting a paternally inherited nucleic acid of fetal origin performed on a maternal serum or plasma sample from a pregnant female, which method comprises

amplifying a paternally inherited nucleic acid from the serum or plasma sample and

detecting the presence of a paternally inherited nucleic acid of fetal origin in the sample.

Ariosa, 778 F.3d at 1373-74. The court concluded that this claim was little more than a general method for detecting naturally occurring cffDNA. Id. at 1376.

This conclusion even applied to claim 25, below, which describes performing a diagnosis and the prior art did not recognize that maternal blood could be collected, that paternal DNA in that blood could be amplified or that paternally inherited DNA could be analyzed in that sample. Id.

25. A method for performing a prenatal diagnosis on a maternal blood sample, which method comprises

obtaining a non-cellular fraction of the blood sample

amplifying a paternally inherited nucleic acid from the non-cellular fraction

and performing nucleic acid analysis on the amplified nucleic acid to detect paternally inherited fetal nucleic acid.

Id. at 1374. There were no dependent claims to narrow the steps of claim 25.

The Federal Circuit confirmed that the '540 Patent's claims represented unpatentable subject matter:

the asserted claims of the '540 patent are directed to a multistep method that starts with cffDNA taken from a sample of maternal plasma or serum — a naturally occurring non-cellular fetal DNA that circulates freely in the blood stream of a pregnant woman. ... a natural phenomenon. ...it is undisputed that the location of the nucleic acids existed in nature before Drs. Lo and Wainscoat found them. The method ends with paternally inherited cffDNA, which is also a natural phenomenon. The method therefore begins and ends with a natural phenomenon. Thus, the claims are directed to matter that is naturally occurring.

Id. at 1376 (emphasis added). That the same DNA was there at both the start and end of the method and was inherently there during past methods, even if not recognized, seems to have influenced the decision.

In his concurrence, Judge Richard Linn expressed his disappointment that he felt "bound by the sweeping language of the test set out in Mayo." Id. at 1380.

The Supreme Court's blanket dismissal of conventional post-solution steps leaves no room to distinguish Mayo from this case, even though here, no one was amplifying and detecting paternally-inherited cffDNA using the plasma or serum of pregnant mothers. Indeed, the maternal plasma used to be "routinely discarded."

Id. at 1381 (Linn concurrence) (emphasis added).

Rapid Litigation Gives Hope to Patentees

The Federal Circuit's analysis in Rapid Litigation helps show how certain claims can survive both Mayo steps (1) and (2). The invention claimed in Pat. No. 7,604,929 (the '929 patent) related to a method of processing hepatocytes, a type of liver cell that is useful for testing and treatment purposes. 2016 WL 3606624, at *1. Although freezing the cells was a desirable way to prolong their usefulness, prior to the '929 patent, it was believed that hepatocytes could only be frozen once. Id. The inventors discovered that some hepatocyte cells could be refrozen and a identified a method for collecting and refreezing those cells.

Claim 1 is illustrative:

1. A method of producing a desired preparation of multi-cryopreserved hepatocytes, said hepatocytes, being capable of being frozen and thawed at least two times, and in which greater than 70% of the hepatocytes of said preparation are viable after the final thaw, said method comprising:

(A) subjecting hepatocytes that have been frozen and thawed to density gradient fractionation to separate viable hepatocytes from non-viable hepatocytes,

(B) recovering the separated viable hepatocytes, and

(C) cryopreserving the recovered viable hepatocytes to thereby form said desired preparation of hepatocytes without requiring a density gradient step after thawing the hepatocytes for the second time, wherein the hepatocytes are not plated between the first and second cryopreservations, and wherein greater than 70% of the hepatocytes of said preparation are viable after the final thaw.

Id. at *2.

The district court ruled that under step (1) the '929 patent was directed to an unpatentable law of nature. ("that [some] hepatocytes are capable of surviving multiple freeze-thaw cycles"); and that under step (2), the individual steps of the claimed method were conventional. Id.

The Federal Circuit reversed. The court concluded that although the claims involved a natural law, they were not "directed to" that natural law, but to a process deriving its benefit from that natural law. Id. at *4. The Rapid Litigation panel indicated that in Ariosa, the presence of cffDNA in blood or serum was natural and the steps merely identified what was naturally present. The court in Ariosa may have been influenced by the lack of specificity or transformation and considered the claims to be nothing more than an artful way of indicating that the natural phenomenon should be applied, but without indicating how.

The court considered the '929 patent's claims to recite more than the ability of hepatocyte cells to survive multiple freeze-thaw cycles.

Through the recited steps, the patented invention achieves a better way of preserving hepatocytes. ... That one way of describing the process is to describe the natural ability of the subject matter to undergo the process does not make the claim "directed to" that natural ability.

Id at *4. The court also stated that Mayo has been interpreted too narrowly: "Indeed, to preclude the patenting of an invention simply because it touches on something natural would 'eviscerate patent law.'" Id. at *6, citing Mayo, 132 S.Ct. at 1293.

The Rapid Litigation panel's discussion of Mayo step (2), i.e., whether the steps amounted to an inventive concept, is also illustrative. The court acknowledged that each of the individual steps of the method (freezing, thawing and separating) were conventional. Id., citing Mayo, 132 S.Ct. at 1298. However, the court clarified that under Mayo step (2), the claim steps are not looked at in isolation, but in combination. Id. at *6, citing Alice Corp. v. CLS Bank Int'l, 134 S.Ct. 2347, 2355 (2014). The court explained that whereas performing freeze-thaw cycles may be known, repeating the freeze-thaw cycle with hepatocytes was not. Id. at *7. Similarly, a gradient centrifugation separation step after the first freeze-thaw cycle of hepatocytes was new.

Finally, the court explained that patent eligibility and obviousness should be examined under separate provisions of the patent act. Rapid Litigation, 2016 WL 3606624, at *7, citing Mayo, 132 S.Ct at 1304. Unfortunately, the court stopped short of clarifying that indefiniteness under § 112 also warrants a separate analysis.

Lessons From the Claim Comparison

An element-by-element comparison (with the benefit of hindsight) can help illustrate the differences between claim 25 of the Ariosa '540 patent and claim 1 of the Rapid Litigation '929 patent.

'540 Preamble:

25. A method for performing a prenatal diagnosis on a maternal blood sample, which method comprises ...

'929 Preamble:

1. A method of producing a desired preparation of multi-cryopreserved hepatocytes, said hepatocytes, being capable of being frozen and thawed at least two times, and in which greater than 70% of the hepatocytes of said preparation are viable after the final thaw, said method comprising ...

The '540 patent's preamble is more general than the '929's. For example, the '540 claim contains no description of the type of prenatal diagnosis. In contrast, the '929 preamble very specifically describes producing hepatocytes that are capable of being frozen and thawed at least two times with greater than 70 percent viability. A reasonable conclusion is that the more specific a claim, the less likely the court should conclude that it is directed to a natural law. In addition, the '929 patent's claim describes transformations that occur during performance of the method, whereas the '540 patent's claim does not.

Turning to the individual claim steps:

Steps of '540 Claim 25:

obtaining a non-cellular fraction of the blood sample

amplifying a paternally inherited nucleic acid from the non-cellular fraction

performing nucleic acid analysis on the amplified nucleic acid to detect paternally inherited fetal nucleic acid.

Step (A) of 929 Claim 1:

(A) subjecting hepatocytes that have been frozen and thawed to density gradient fractionation to separate viable hepatocytes from non-viable hepatocytes.

The court in Ariosa concluded that the claim steps do not describe how the non-cellular fraction is obtained, nor how one is to go about amplifying the paternally inherited nucleic acid from the noncellular fraction. Similarly, claim 25 does not specify the type of analysis to be performed, nor how the nucleic acid is detected. It appears that such generality makes it more likely a court will conclude that the individual steps do not support patentability.

In contrast, '929 patent claim 1 specifies performing density gradient fractionation; and not on any collection of hepatocytes, but to hepatocytes that had been frozen and thawed. The court also found it noteworthy that "[a]dditional dependent claims are directed to the type of density gradient fractionation, the type of hepatocytes, viability, and pooling." Id. at *2.

Another important lesson is to include claims of varying scope. Although it may be useful to obtain broad claims by describing features with generality, each of those broad steps should be narrowed in dependent claims to define increasingly specific methods or products.

Finally, in Ariosa, the court explained that with respect to the claims, the method "begins and ends with a natural phenomenon." Ariosa, 788 F.3d at 1376. In contrast, the '929 claims begin with hepatocytes that have been frozen, then subject them to a separation step, then end with a new preparation having a higher percentage of viable cells than when the method started. Rapid Litigation, 2016 WL 3606624, at *5. It should not be forgotten that in Bilski v. Kappos, 130 S.Ct. 3218, 3227 (2010), the court indicated that the "machine-or-transformation test is a useful and important clue, an investigative tool, for determining whether some claimed inventions are processes under § 101." Rapid Litigation confirms that a claim that describes a transformation may be more likely to be upheld than one where no change to the starting material is described. 2016 WL 3606624, at *4-5.


The application of law of nature exception to patentable subject matter clearly involves unpredictability. However, increasing specificity, describing transformations, adding claims of varying scope and recognizing that claims must be considered as a whole should increase the chance of a patent being upheld.

By Matthew Siegal, Stroock & Stroock & Lavan LLP, a partner in Stroock's Intellectual Property Practice Group in New York.

Matthew Siegal will be speaking at the Centerforce IP Strategy Summit NYC 2016 on October 27, 2016.  For further details, Click Here

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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