The Supreme Court ruled earlier this year in the long-running Bilski case, in which inventors wanted to patent methods for hedging energy costs based on weather predictions.
The Court said that the Bilski invention could not be patented but did not issue the widely-expected clear guidance on the confused area of software and business method patent law.
The ruling did, though, say that a test – whether the invention changed a machine or caused a transformation in something – was useful only as a guide and not as the absolute arbiter of what can and cannot be patented.
The USPTO has issued new guidance for its patent examiners for consultation based on the ruling.
"This Interim Bilski Guidance is for determining patent eligibility of process claims under 35 USC 101 [the part of US patent law which identifies what kinds of invention are patentable] in view of the opinion by the Supreme Court in [the Bilski case], which refined the abstract idea exception to subject matter that is eligible for patenting," said the guidance.
"In order for the examiner to make a proper prima facie case of ineligibility, the examiner will evaluate the claim as a whole and weigh the relevant factors set forth in Bilski and previous Supreme Court precedent and make a determination of compliance with the subject eligibility prong of [the law]," it said.
The USPTO has told its patent examiners that the Bilski case is likely to widen the scope of what can be patented under US law.
"The Bilski Court underscored that the text of [section] 101 is expansive, specifying four independent categories of inventions eligible for protection, including processes, machines, manufactures, and compositions of matter," it said.
"The Court also made clear that business methods are not 'categorically outside of [section] 101’s scope,' stating that 'a business method is simply one kind of 'method' that is, at least in some circumstances, eligible for patenting under [section] 101'," said the USPTO.
The guidance said that though the ruling had broadened the law's scope, that only went so far.
"There are limits on the scope of patent-eligibility. In particular, the Supreme Court has identified three specific exceptions to [section] 101’s broad patent-eligibility principles: Laws of nature, physical phenomena, and abstract ideas," it said.
The USPTO is having to change its guidance and procedures on deciding what should and should not be patentable because the Court's ruling binds it to do so.
"The Office has been using the so-called 'machine-or-transformation' test used by the Federal Circuit to evaluate whether a method claim qualifies as a statutory patent-eligible process," it said. "The Supreme Court stated in Bilski that the machine-or-transformation test is a 'useful and important clue' and 'investigative tool' for determining whether some claimed methods are statutory processes, but it 'is not the sole test for deciding whether an invention is a patent-eligible ‘process'."
The guidance emphasised, though, that there are other factors that patent examiners must consider when deciding on a patent application, and that they must remember to apply all the patent laws, not just those affected by the Bilski ruling.
"Examiners should avoid focusing on issues of patent-eligibility under [section] 101 to the detriment of considering an application for compliance with the requirements of [other sections of the law], and should avoid treating an application solely on the basis of patent-eligibility under [section] 101 court's ruling," it said.
In saying that the machine-or-transformation test is not now to be the only test applied, the guidance opens up the possibility that an invention that fails that test can still be patented. It said, though, that this has not yet happened.
"To date, no court, presented with a subject matter eligibility issue, has ever ruled that a method claim that lacked a machine or a transformation was patent-eligible. However, Bilski held open the possibility that some claims that do not meet the machine-or-transformation test might nevertheless be patent-eligible," it said.
