AMP v. PTO Casts Doubt on Patent Eligibility of "Purified" (as Opposed to "Isolated") Biomolecules

On January 5, 2001, the US PTO published Utility Examination Guidelines explaining its long-standing policy of treating "isolated and purified" DNA molecules as patent eligible. Throughout the Guidelines, the PTO consistently refers to these patent-eligible DNA molecules as both isolated and purified, but never explicitly attributes distinct meaning to the two terms. Instead, I think most people have interpreted the terms (as used by the PTO in this context) as essentially redundant, similar to someone referring to a contract provision as "null and void."

If anything, the PTO guidelines might be interpreted as treating "purification" as a more demanding requirement than "isolation." For example, at one point the guidelines state that "an inventor's discovery of a gene can be the basis for a patent on the genetic composition isolated from its natural state and processed through purifying steps that separate the gene from other molecules naturally associated with it,” perhaps implying that mere isolation will not be sufficient unless the DNA molecule is not subsequently purified through processes that separate the gene from other molecules.

In practice, it is my experience that the PTO and most practitioners have interpreted "purification" and "isolation" as essentially redundant. While most "gene patents" recite DNA molecules that are "isolated," "isolated and purified," or "recombinant," there are a substantial number of issued patents that simply recite "purified" DNA molecules. See for example US Patent Nos. 5,780,262, 6,262,247, 6,399,371, 6,448,042 and 6,555,347. The PTO also routinely issues patents on other purified biomolecules, particularly proteins, based no doubt on the assumption that as a general matter purification of a biomolecule from its native environment is sufficient to confer patent eligibility. See for example US Patent Nos. 6,258,556 and 6,284,236.

In the Federal Circuit's recent decision in AMP v. PTO (discussed briefly already on Patently-O and Patent Docs), the two judges in the majority (Lourie and Moore) held that "isolated" DNA molecules are patent eligible, but implied that mere "purification" of a biomolecule is insufficient to render it patent eligible. Writing for the majority, Judge Lourie correctly observes that patent eligibility under 35 USC 101 of purified biomolecules has never been explicitly addressed by the courts. As I pointed out in an earlier blog post:

The cases most commonly cited for the proposition that a purified naturally occurring compound is patent eligible are In re Kratz, 592 F.2d 1169, 1174 (CCPA 1979) (stating that a naturally occurring strawberry constituent compound does not anticipate claims to the substantially pure compound) and In re Bergstrom, 427 F.2d 1394 (CCPA 1970) (stating that a material occurring in nature in less pure form does not anticipate claims to the pure material). The Federal Circuit implicitly seems to support this view, and as recently as 2003 a Federal Circuit panel cited both Kratz and Bergstrom with apparent approval. But it is worth noting that Kratz and Bergstrom dealt specifically with the novelty and nonobviousness of the compounds, not patent eligibility per se. To my knowledge, there is no judicial precedent that has directly addressed the issue of whether isolation of a naturally occurring molecule renders the isolated molecule and eligible under section 101.

Judge Lourie also correctly noted that the Supreme Court's decision in Funk Bros., although often treated as patent eligibility case, was actually decided on the basis of obviousness, a point that Hal Wegner has long made in which I discussed in a previous blog post.


In what might be the most interesting part of the decision, Judge Lourie makes a clear distinction between purification and isolation of DNA. He explicitly states that "isolated DNA is not purified DNA." In his view, “[p]urification makes pure what was the same material, but was previously impure,” while “[i]solated DNA, in contrast, is a free-standing portion of a native DNA molecule, frequently a single gene. Isolated DNA has been cleaved (i.e., had covalent bonds in its backbone chemically severed) or synthesized to consist of just a fraction of a naturally occurring DNA molecule.”

Judge Lourie stresses that unlike a biomolecule that has been merely purified, isolated DNA "has also been manipulated chemically so as to produce a molecule that is markedly different from that which exists in the body." In his view, the test for patent eligibility hinges on whether the claimed molecule is "markedly different" from that which occurs in nature, and differences at the level of chemical structure between synthetic DNA, or genomic DNA that has been excised from the genome, are sufficient to satisfy the test. Implicitly, he seems to suggest that purified DNA molecules that are not structurally distinct from a naturally occurring counterpart would not be patent eligible. This seems to suggest that claims directed towards purified biomolecules, such as proteins, might not be patent eligible.

In its amicus brief, as I recall, the Biotechnology Industry Organization argued that the District Court's decision in AMP v. PTO should be reversed because it implied that a purified natural product, such as Taxol, would be patent ineligible under the logic of the decision. But in fact it seems that even though the Federal Circuit reversed on the patentability of isolated DNA, its decision suggests that a purified natural product is patent ineligible unless it has distinctions in chemical structure sufficient to render it "markedly different" from its naturally occurring counterpart.

Arguably, the Federal Circuit's decision in AMP v. PTO is not inconsistent with the PTO utility examination guidelines. For example, the guidelines provide two examples of patent eligible isolated DNA - DNA that has been chemically synthesized outside of the body, and DNA that has been excised from the chromosome. Judge Lourie explicitly identifies these two forms of DNA as "isolated" and hence patent eligible.

Judge Lourie and Judge Moore get mixed up at times on the nuances of molecular biology, and make some misstatements regarding the nature of genomic DNA and cDNA. However, while a molecular biologist will pick up on these inaccuracies, I don't think they detract from the core of the decision. In a previous blog post, I explained why the amicus brief filed by the DOJ attempting to distinguish between cDNA and genomic DNA missed the mark because it failed to recognize that, in the vast majority of cases, "isolated" DNA refers to DNA that has been synthesized outside of the native context from which it arose in the body. The DOJ brief (which Judge Moore described as being at times “childlike” in its simplicity) assumed wrongly that "isolated" genomic DNA has merely been plucked from the human cell (what Judge Lourie would characterize as purification), when in fact patents on isolated DNA are based on DNA molecules that have been synthesized in the laboratory, either by cloning into a host cell, or by PCR, or something along those lines. I think that at some level Judge Lourie’s decision gets at this distinction between a biomolecule that has merely been purified, and isolated DNA molecules, which are generally the result of human-directed synthesis.