What happened
AstraZeneca AB was the registered proprietor and AstraZeneca Pty Ltd the exclusive licensee of Australian Patent 051 entitled "Use of Cholesterol-Lowering Agent". The patent claimed methods of treating hypercholesterolemia by administering rosuvastatin (or its calcium salt) as a starting dose of 5-10 mg once daily (claims 1 and 2), with claim 3 adding patient-selection criteria based on LDL-C levels and cardiovascular risk factors. The priority date was 6 February 1999. The specification acknowledged that rosuvastatin itself had been disclosed in European Patent 471 (published 1993, priority 1991) and in the 1997 Watanabe Article. Both documents identified the compound as a potent HMG-CoA reductase inhibitor but neither formed part of common general knowledge at the priority date, nor did the chemical structure or name "rosuvastatin".
Three generic companies—Apotex Pty Ltd, Watson Pharma Pty Ltd and Ascent Pharma Pty Ltd—began supplying or threatening to supply generic rosuvastatin tablets at the same 5 mg and 10 mg strengths. AstraZeneca sued for infringement. The generics counterclaimed for revocation on multiple grounds, including lack of entitlement (on the basis that Shionogi employees had invented rosuvastatin), lack of novelty over Patent 471 and the Watanabe Article, and lack of inventive step under ss 7(2) and 7(3) of the Patents Act 1990 (Cth) as they stood at the priority date.
Jagot J at first instance revoked the patent on all three grounds. The Full Court of the Federal Court (Besanko, Jessup, Foster, Nicholas and Yates JJ) reversed the novelty finding but upheld the obviousness conclusion and the entitlement finding. AstraZeneca sought and obtained special leave to appeal to the High Court on two grounds: first, that the Full Court had misapplied ss 7(2) and 7(3) in upholding the obviousness finding; second, that the Full Court had erred in refusing leave to amend to rely on a post-judgment assignment from Shionogi and on later-entering entitlement provisions.
The High Court (French CJ, Kiefel, Gageler, Keane and Nettle JJ) heard the matters together. The Commonwealth intervened on the question whether the primary judge had correctly followed Apotex Pty Ltd v Sanofi-Aventis in treating the known existence of rosuvastatin as the "starting point" for the obviousness inquiry. The Court found it unnecessary to decide the entitlement or Sanofi issues. It dismissed the appeals on the inventive-step ground alone, holding that the claims lacked an inventive step when common general knowledge was considered together with either the Watanabe Article or Patent 471. Costs followed the event in each appeal.
The factual matrix was therefore a classic patent validity contest in the statin field at a time when atorvastatin had become the market leader, dose titration was recognised as a practical burden, and the industry was actively searching for more potent molecules that could reach LDL-C targets at the initial prescribed dose.
Why the court decided this way
The Court decided the patent was invalid because the claimed low-dose method would have been obvious to a notional skilled addressee equipped with the common general knowledge plus either piece of s 7(3) information. French CJ (with whom the other justices agreed on the result) began by setting out the statutory text. Section 7(2) provides that an invention is taken to involve an inventive step unless it would have been obvious to a person skilled in the relevant art in the light of common general knowledge considered separately or together with prior art information of the kind mentioned in s 7(3), each of which must be considered separately. Section 7(3)(a) limits that information to prior art made publicly available in a single document that the skilled person could reasonably be expected to have ascertained, understood and regarded as relevant.
The decisive construction point was AstraZeneca's argument that the phrase "considered separately" in s 7(2) forbade any comparative reference to other non-common-general-knowledge documents when deciding whether a particular document satisfied the s 7(3) relevance filter. The Court rejected that reading. Jessup J's Full Court reasoning (expressly approved) was that the skilled person must be allowed to "sort through all manner of information with a view to finding something that is 'regarded as relevant'". Nothing in s 7(3) places an embargo on using combinations of sources on the road to that destination. The "considered separately" requirement operates only at the later stage when the court asks whether the invention is obvious once the qualifying document has been added to common general knowledge; it prevents mosaicking of unrelated documents but does not sterilise the search process itself.
With that construction settled, the Court turned to the evidence. The hypothetical skilled addressee was a medical practitioner with specialised expertise in treating hypercholesterolemia and lipidology. Common general knowledge at the priority date included: (a) the mechanism of statins as HMG-CoA reductase inhibitors; (b) the available statins (fluvastatin 20-40 mg, pravastatin 5-40 mg, simvastatin 5-40 mg, atorvastatin 10-40 mg); (c) the standard practice of starting at the lowest dose to minimise adverse events and titrating upward over months with repeated blood tests and visits; (d) the consequent failure of many patients to reach targets because titration was burdensome; and (e) the consequent desirability of a statin that brought more patients to target at the starting dose.
Neither the name nor structure of rosuvastatin was in that body of knowledge. However, routine literature searches prompted by the known problem would have located the Watanabe Article. That article identified S-4522 (rosuvastatin) as possessing greater enzyme inhibitory activity than lovastatin and pravastatin, approximately 100-fold more potent than pravastatin in rat hepatocytes, four times more potent than lovastatin in vitro, and more effective than pravastatin in lowering plasma cholesterol in beagle dogs and cynomolgus monkeys. It stated that clinical trials were in progress and that the compound was liver-selective, suggesting reduced side effects. Professor O'Brien (accepted as representative of the skilled person) gave evidence that he would have selected this compound over NK-104 (the subject of the Aoki Article) because it had progressed further and showed superior potency with reduced side-effect potential. He would then have performed a patent search, locating the Japanese equivalent of Patent 471, whose English-language version indicated an expected oral dosage range of 0.5-200 mg/day, comfortably encompassing 5-10 mg.
Dr Reece's evidence was to similar effect: the Watanabe Article identified a "very potent inhibitor of cholesterol biosynthesis" and "definitely a candidate for further development". Both experts regarded dose-ranging studies in humans as conventional once a promising compound had reached that stage. The Court held that testing at the lowest conventional doses (5 mg, 10 mg, 20 mg) to establish safety and efficacy fell squarely within "working towards the invention with an expectation of success" (citing AB Hässle). The absence of animal or human safety data in the two documents was not fatal; such data would be generated by the routine trials the skilled person would undertake.
The primary judge and the Full Court had correctly applied the adapted Cripps question: would the notional skilled person be directly led as a matter of course to try the claimed invention in the expectation that it might well produce a useful alternative or better drug than existing statins? The answer was yes. Secondary evidence of commercial success of Crestor and the failure of others to reach the precise claims was discounted because, once the skilled person is notionally given the Watanabe Article or Patent 471, the factual setting changes; the notional inquiry "need not correspond with reality".
Kiefel J, Gageler, Keane and Nettle JJ wrote concurring reasons that reinforced the same analysis. The result was that the invention did not involve an inventive step. The appeals were dismissed with costs.
Before and after state of the law
Before the 1990 Act, obviousness was governed by s 100(1)(e) of the 1952 Act, which asked whether the claim was obvious and did not involve an inventive step having regard to what was known or used in Australia on or before the priority date. That language was interpreted as requiring the prior disclosure to form part of common general knowledge; documents not within common general knowledge could not be combined with it (Minnesota Mining; Wellcome Foundation). The "Cripps question" from Olin Mathieson, adopted in Wellcome and AB Hässle, asked whether the notional non-inventive worker equipped only with common general knowledge would take routine steps leading to the invention. Mosaicking of prior publications was forbidden.
The 1990 Act raised the threshold for inventiveness. Sections 7(2) and 7(3) expressly permitted common general knowledge to be supplemented by prior art information in a single document (or related documents treated as one source) provided the skilled person could reasonably be expected to have ascertained, understood and regarded that information as relevant. The IPAC recommendations that led to the provision made clear that the new prior-art base was intended to include disclosures a skilled person should reasonably have been expected to find, understand and regard as relevant. The government response qualified the recommendation but preserved the core idea that a single qualifying document could be added to common general knowledge.
This case is the High Court's authoritative statement on the boundaries of that widened inquiry. It confirms that the ascertainment step under s 7(3) is not artificially cabined; the skilled person may review multiple documents to decide which one is relevant. Once relevance is established, however, the obviousness test proceeds with common general knowledge plus that single document only. The Court emphasised that the content of the inventive-step requirement itself was not altered: the test remains whether the skilled person would, as a matter of routine, be led from the prior art to the claimed invention. What changed was the permissible prior-art base against which that test is applied. After this decision, Australian obviousness law operates with a clearer two-stage filter: first, identify any qualifying s 7(3) document(s) (allowing comparative searching), then ask the obviousness question separately for each such document combined with common general knowledge.
Key passages with plain-English translation
French CJ at the introduction: "Sections 7(2) and 7(3) are central to these appeals… They defined the condition on satisfaction of which an invention would not be taken to involve an inventive step."
Plain English: The whole case turns on how to read the obviousness provisions. If the claimed low-dose method would have been obvious to an ordinary doctor or researcher who knew the everyday knowledge in the field plus one relevant old paper or patent, then the patent is invalid.
French CJ quoting Jessup J: "It is, in my view, wholly within the scheme of the subsection that [the skilled person] might well sort through all manner of information with a view to finding something that is 'regarded as relevant'. There is nothing in the provision which would place an embargo upon the skilled person using combinations of sources of information along the road to that destination."
Plain English: When deciding whether an old scientific paper is relevant enough to count, the researcher is allowed to look at several papers, compare them, and discard the less promising ones. The statute does not force the researcher to pretend he or she has never seen the other papers.
French CJ on the test: "whether the notional research group at the relevant date, in all the circumstances… directly be led as a matter of course to try [the claimed inventive step] in the expectation that it might well produce a useful alternative to or better drug than [the existing compound]?"
Plain English: Would an ordinary, non-inventive lipid expert who read the Watanabe Article think "I should test this new statin at the usual low doses to see if it works better than atorvastatin"? If yes, the invention is obvious.
French CJ on secondary evidence: "the extended form of s 7(2) sets up a notional inquiry which need not correspond with reality… Once we equip the notional worker with the Watanabe article or the 471 patent, the whole setting in which the Cripps question must be asked is altered."
Plain English: The fact that no real company reached the exact 5-10 mg claims before AstraZeneca does not prove inventiveness, because the law asks what a hypothetical expert would do if given the old papers. In that hypothetical world the expert would have gone straight to the claimed doses.
Kiefel J: "The evidence therefore shows that the skilled person would be led to the invention."
Plain English: Once the two documents are added to everyday medical knowledge, the path to the patented low-dose method is routine clinical development work, not a patentable invention.
What fact patterns trigger this precedent
This precedent is triggered whenever a patent claim is challenged for obviousness and the challenger relies on common general knowledge plus one or more prior art documents that were not themselves part of common general knowledge at the priority date. The key factual ingredients are:
- A well-known problem in the art (here, the practical burden and incomplete efficacy of dose titration of marketed statins);
- Routine search strategies that a skilled person would employ to solve that problem (literature searches for more potent statins, patent searches once a promising molecule is identified);
- One or more single documents that a court can find would have been ascertained, understood and regarded as relevant;
- Evidence that the skilled person, armed with that document, would take routine steps (pre-clinical testing, dose-ranging studies, Phase I/II trials) that lead directly to the claimed invention with a reasonable expectation of success.
The precedent applies with particular force in pharmaceutical method-of-treatment cases where the active compound is already disclosed in the literature but the patent asserts a new dosage regimen or patient-selection criterion said to solve a known clinical problem. It also applies where the patentee relies on secondary indicia (commercial success, long-felt want, failure of others); the Court made clear that such evidence may be discounted if the notional skilled person equipped with the s 7(3) document is in a different factual position from real-world researchers.
The fact pattern will not trigger the precedent where the prior art document cannot reasonably be ascertained (for example, an obscure unpublished thesis) or where the step from the document to the claim requires inventive ingenuity rather than routine work.
How later courts have treated it
The judgment itself carefully positioned the decision as consistent with, and an application of, the earlier authorities. It followed the obviousness test articulated by Aickin J in Wellcome Foundation Ltd v VR Laboratories (Aust) Pty Ltd and the refined Cripps question approved in Aktiebolaget Hässle v Alphapharm Pty Ltd. It cited Lockwood Security Products Pty Ltd v Doric Products Pty Ltd [No 2] for the explanation of "ascertained, understood and regarded as relevant" and for the proposition that the 1990 Act raised the threshold of inventiveness. It distinguished the Full Court decision in Apotex Pty Ltd v Sanofi-Aventis on the "starting point" question, finding it unnecessary to decide the correctness of that case because the evidence showed the skilled person would have discovered rosuvastatin in any event.
The Court rejected any suggestion that the "single avenue" approach created an impermissible hindsight analysis. It emphasised that the statutory text does not require the court to hypothesise every false route that might have been taken; once the most promising candidate is identified and routine steps lead to the claim, obviousness is established. Nettle J added that, when assessing obviousness itself, information from other documents must be excluded; only common general knowledge and the contents of the single s 7(3) document may be used. This refinement has become the orthodox understanding of the two-stage process.
The judgment also confirmed that the skilled person is a legal construct, not a real person, and that expert evidence is relevant only insofar as it illuminates what that construct would do. Courts after this decision have therefore been careful to separate the evidence used to satisfy s 7(3) from the evidence used to answer the ultimate obviousness question.
Still-open questions
The Court expressly left two significant issues undecided. First, the entitlement ground was not determined because the obviousness conclusion was sufficient to dispose of the appeals. The interlocutory application to rely on a post-judgment assignment from Shionogi and on subsequently enacted relieving provisions was refused, but the substantive entitlement question remains unanswered in this proceeding.
Second, the correctness of the Full Court's earlier decision in Apotex Pty Ltd v Sanofi-Aventis concerning the proper "starting point" for the obviousness inquiry when the existence of the active compound is known but not part of common general knowledge was not resolved. The Commonwealth intervened because of pending damages proceedings that turned on that point. The Court noted that the evidence in the present case showed the skilled person would have found rosuvastatin in any event, making it unnecessary to decide whether the primary judge had erred in treating the compound as a given. That controversy therefore remains live for future cases.
A further open question flows from the Court's emphasis on the notional character of the s 7(2) inquiry. How far courts may depart from real-world events when weighing secondary indicia remains a matter of degree to be worked out case by case. The judgment states that Australian courts have long recognised that the importance and weight of such evidence "will vary from case to case and it will not necessarily be determinative", but gives no bright-line rule for when the notional equipping of the skilled person with a s 7(3) document so alters the factual landscape that secondary evidence becomes irrelevant.
Finally, the precise boundaries of what constitutes "routine" work in complex fields such as clinical pharmacology are not exhaustively defined. While dose-ranging studies were held routine on the evidence in this case, future disputes may test whether more elaborate or high-risk development pathways cross the line into inventive activity. The statutory text and the Wellcome/AB Hässle framework remain the touchstones, but their application will continue to be heavily evidence-dependent.