Key takeaways

  • Interlocutory injunctions remain a viable tool for patentees: Recent decisions confirm that originator pharmaceutical companies can still obtain interlocutory injunctions to restrain the launch of a first generic or biosimilar product, reversing the post-2018 trend against the grant of such relief.
  • Strength of the prima facie infringement case is critical: A consistent distinguishing factor between successful and unsuccessful applications has been the strength of the patentee’s prima facie case on infringement, and whether that case is undermined by the respondent’s invalidity arguments.
  • Difficulty in quantifying loss is no longer determinative: The complexities of proving loss are now regarded as finely balanced between both parties, meaning the inherent difficulties faced by generic or biosimilar parties in this regard should not always defeat an application for an interlocutory injunction.
  • Broader balance of convenience factors can be decisive: Patentees should consider evidence concerning the significance of the status quo and third-party harm, especially in cases where other balance of convenience factors are finely balanced.

Background

Prior to 2018, the majority of interlocutory injunction applications concerning pharmaceutical patents were successful. A common feature of most of these cases was a finding that the balance of convenience favoured patentees, due to automatic (and presumably irreversible) statutory price reductions caused by the listing of a first generic (or biosimilar) product on the Pharmaceutical Benefits Scheme (PBS).

Following the 2018 first instance and Full Court decisions in Sanofi v Alphapharm[1], however, the pendulum started to swing against innovators, with the Federal Court refusing to grant an interlocutory injunction in relation to injector pens containing insulin glargine.

The trend against the grant of interlocutory injunctions in pharmaceutical patent cases may be traced to remarks made by Justice Jagot earlier in 2018 in Sigma.[2] In that matter, the patentee had obtained an interlocutory injunction in 2009 and, almost a decade later, her Honour was required to quantify the generic party’s claim for compensation pursuant to the patentee’s undertaking as to damages, after the patentee failed to establish infringement of a valid patent. Justice Jagot observed that, with hindsight:

it could never have been concluded, for example, that insofar as relevant to the balance of convenience it would be easier for the generics to prove their loss if the interlocutory injunctions were wrongly granted than for [the patentee] to prove its loss if the interlocutory injunctions were withheld and the method patent was valid.[3]

Subsequent cases appeared to accept that generic/biosimilar parties will always face greater difficulty in quantifying loss compared to patentees, and contested applications for interlocutory injunctions were, until recently, refused. Generic and biosimilar parties successfully raised difficulties in assessing matters such as the market share a generic/biosimilar product would have obtained, the competitive response from other generic/biosimilar companies, and the pricing behaviour of suppliers in the market.

Significantly, however, recent Federal Court decisions in Biogen[4] and Regeneron[5] have acknowledged that the complexities of proving loss are finely balanced as between patentees and generics/biosimilars. For example, Rofe J in Regeneron noted that it was not possible to conclusively determine that the complexity of estimating the loss of one side was greater than the other. In that case, however, her Honour accepted that the generic party faced the greater number of unknowns in claiming loss pursuant to the undertaking as to damages, than the patentee would face if no interlocutory injunction was granted.

Against this background, two recent decisions, less than three months apart, found in favour of granting interlocutory injunctions against the generic party: Janssen v Juno[6] and AstraZeneca v Pharmacor.[7] These decisions are significant because they confirm that the uncertainties in calculating loss are finely balanced as between patentees and generic or biosimilar companies, and serve as a reminder that irreparable harm is but one of the factors to consider in the balance of convenience exercise.[8] Consequently, other factors in the balance of convenience, such as the strength of the prima facie case or third party harm, may be decisive.

Janssen v Juno

Janssen supplies in Australia prescription medicines for the treatment of schizophrenia, containing the active ingredient paliperidone palmitate. Janssen is the patentee of a patent concerning dosing regimens associated with long acting injectable paliperidone esters, including paliperidone palmitate.

Juno is the sponsor of two long acting injectables containing paliperidone palmitate. Janssen contended that Juno’s launch of these generic products would infringe its patent. Accordingly, Janssen sought interlocutory orders to restrain Juno from exploiting its generic products and listing them on the PBS, pending final determination of patent infringement proceedings.

The well-established principles for granting interlocutory injunctions, particularly in patent infringement cases, were summarised by the Full Court in Samsung.[9]

The two-step approach involves first, an assessment of a prima facie case of patent infringement; and second, whether the balance of convenience favours granting the relief sought. Importantly, the strength of the prima facie case is a relevant factor in the assessment of the balance of convenience.[10] Other balance of convenience factors can include: the adequacy of damages as a remedy for either party; whether the alleged harm is irreparable or not readily quantifiable; preservation of the status quo versus disruption to the respondent’s business, product launch or supply chains; delay in seeking relief; effects on third parties and the public interest; and any arguable invalidity case.

Janssen contended that the balance of convenience favoured the grant of the interlocutory injunction including because, if Juno was not restrained:

(1) Janssen would suffer significant and irreversible price reductions for its three paliperidone palmitate products;

(2) it would lose market share and suffer very significant losses the magnitude of which would be difficult to quantify; and

(3) the loss of sales would lead to other consequences, such as reductions in expenditure supporting the sales of its paliperidone palmitate products and damage to its goodwill.

Juno submitted that if the interlocutory injunction was granted, it would suffer significant losses, in particular the loss of first mover advantage. Juno also contended that Janssen’s patent was due to expire in December 2028, that the magnitude of Janssen’s potential loss was not as great as Janssen contended, and that in any event, calculating damages on the undertaking would be more difficult than calculating damages if Janssen’s infringement case succeeded.

Justice Burley acknowledged that calculating Juno’s damages if an interlocutory injunction was granted, would be inherently more difficult than calculating Janssen’s damages if no injunction was granted and Janssen’s patent was infringed. Despite this, his Honour concluded that granting the interlocutory injunction was appropriate, taking into account factors including the strength of Janssen’s prima facie infringement case.

AstraZeneca v Pharmacor

AstraZeneca AB is the patentee of a patent relating to dapagliflozin, which is used for the treatment of diabetes, chronic kidney disease and heart failure. AstraZeneca Pty Ltd supplies dapagliflozin in Australia under the brand name FORXIGA, as well as combination products containing dapagliflozin.

Pharmacor sought to list generic dapagliflozin products on the PBS with effect from 1 April 2026.

AstraZeneca commenced proceedings against Pharmacor, alleging that Pharmacor’s generic dapagliflozin products would infringe its patent (and consequently, contravene the Australian Consumer Law), and sought an interlocutory injunction restraining Pharmacor from exploiting those products, including withdrawing the PBS listing application.

Pharmacor did not dispute that their products fell within the scope of the AstraZeneca’s patent.  Pharmacor resisted the grant of the interlocutory injunction on the basis that AstraZeneca’s patent was invalid on the grounds of lack of novelty, lack of inventive step, and was not a manner of manufacture. Further, Pharmacor submitted that the balance of convenience did not favour the grant of the injunction.

Downes J was satisfied that AstraZeneca had a prima facie case of infringement and that Pharmacor’s grounds of invalidity did not diminish the strength of that prima facie case.

Turning to the balance of convenience, her Honour referred to the following categories of harm which would be suffered by AstraZeneca if Pharmacor was not restrained:

  1. loss of revenue to AstraZeneca upon market entry of Pharmacor’s generic dapagliflozin products;
  2. diminution of the value of AstraZeneca’s property rights would be an irreparable harm, noting that AstraZeneca acquired the patent from Bristol-Myers Squibb Co in 2014;
  3. immediate 25% price reduction to the price of FORXIGA on the PBS, and long-term pricing implications as a result of the price disclosure regime;
  4. loss of opportunity to AstraZeneca to mount an effective authorised generic strategy; and
  5. organisational harm to AstraZeneca and to third parties.

On the other hand, if Pharmacor was restrained, her Honour recognised that Pharmacor would lose the first mover advantage, and that there were likely difficulties in assessing what market share Pharmacor would have obtained, but for the injunction.

Taking into account the strength of AstraZeneca’s prima facie case on infringement, which her Honour did not consider to be undermined by Pharmacor’s invalidity attacks, the balance of convenience factors highlighted above, the undertakings offered by AstraZeneca to Pharmacor and third parties, including the Commonwealth, and the fact that the matter was listed for trial commencing 31 August 2026, Downes J concluded that the balance of convenience favoured the grant of the interlocutory injunction.

In reaching this view, her Honour also had regard to the maintenance of the status quo in allowing AstraZeneca to exploit its invention on an exclusive basis, Pharmacor’s commercial decision to engage in conduct that infringes AstraZeneca’s patent, and the purpose of the Australian patent system (to encourage and reward invention).

What does this mean for balance of convenience?

Assessing losses for either party has consistently been found to be complex, time-consuming, and uncertain. In Biogen, Justice Rofe could not provisionally determine whose loss was more complex to estimate.[11] In Regeneron, her Honour expressed a similar view but noted that the unknowns in a restraint scenario suggested greater difficulty in calculating Sandoz’s damages compared to Regeneron’s in a launch scenario.[12]

Despite the accepted complexities in calculating losses for generic or biosimilar companies when an interlocutory injunction is wrongly granted (due to patent invalidity and/or non-infringement), Justice Burley noted in Janssen v Juno that while there “will be significant complexities in calculating any losses to Juno in the restraint scenario, which tend to tilt the scales a little”, “difficulty in calculation does not necessarily equate to uncompensable loss”.[13]

Ultimately, these are considerations in assessing the balance of convenience, alongside other factors such as the strength of the prima facie case.

Indeed, when Biogen, Regeneron, Janssen v Juno and AstraZeneca v Pharmacor are considered together, one consistent distinguishing factor is the strength of the prima facie case on infringement.

  • In Biogen, Justice Rofe accepted Pharmacor’s argument that a strong prospect existed that the extension of the patent’s term was wrongly granted. This alone sufficiently justified denying Biogen’s application for an interlocutory injunction.[14]
  • Similarly, in Regeneron, Justice Rofe found that Regeneron had not established a strong prima facie case of infringement. Her Honour noted a real prospect that Sandoz’s biosimilar aflibercept products, used as directed, would not infringe Regeneron’s patent.[15] Although Regeneron sought leave to appeal and a Full Court hearing was held, the matter settled in November 2025 before a decision was published.
  • In contrast, Justice Burley in Janssen v Juno accepted that Janssen had a strong prima facie case of infringement.[16] While Juno presented arguable cases regarding lack of inventive step[17] and false suggestion,[18] his Honour determined these did not diminish the strength of Janssen’s infringement case.[19] His Honour concluded that an interlocutory injunction was appropriate when the strength of Janssen’s infringement case, together with the balance of convenience factors, were considered.[20] Those factors included the operation of the PBS and applicable statutory price reductions, other harm to Janssen from reduced revenue and expenditure, Juno’s potential first mover advantage, and the complexities of calculating damages for both parties.
  • Similarly, in AstraZeneca v Pharmacor, although Pharmacor was found to have an arguable case on invalidity based on lack of novelty,[21] lack of inventive step,[22] and lack of manner of manufacture,[23] these arguments did not undermine AstraZeneca’s prima facie case on infringement.[24] Her Honour found that the balance of convenience favoured the grant of the injunction, noting that a failure to restrain a party from exploiting generic products, where the party had made a commercial decision to engage in infringing conduct, could undermine the patent system in Australia.[25] Her Honour considered that could have a consequential negative impact on future research and development, and the licensing of patented pharmaceutical products in Australia.

In addition to the strength of the prima facie case, other balance of convenience factors, such as third-party harm and preservation of the status quo, may prove determinative in future cases where irreparable harm and the strength of the prima facie case are evenly balanced.

This article was prepared with Chaye Hartwell and Katherine Petsoglou.

[1] Sanofi-Aventis Deutschland GmbH v Alphapharm Pty Ltd (No 3) [2018] FCA 2060; Sanofi-Aventis Deutschland GmbH v Alphapharm Pty Ltd [2019] FCAFC 28 (Sanofi v Alphapharm FFC).

[2] Sigma Pharmaceuticals (Australia) Pty Ltd v Wyeth [2018] FCA 1556.

[3] Sigma at [1336].

[4] Biogen International GmbH v Pharmacor Pty Ltd [2021] FCA 1591

[5] Regeneron Pharmaceuticals, Inc. v Sandoz Pty Ltd [2025] FCA 1067

[6] Janssen Pharmaceutica NV v Juno Pharmaceuticals Pty Ltd [2025] FCA 1538.

[7] AstraZeneca AB v Pharmacor Pty Ltd [2026] FCA 88.

[8] Samsung Electronics Co. Limited v Apple Inc. [2011] FCAFC 156, [61].

[9] Samsung Electronics Co. Limited v Apple Inc. [2011] FCAFC 156.

[10] See e.g., Sanofi v Alphapharm FFC at [8].

[11] Biogen [259].

[12] Regeneron [312]. See also Janssen v Juno [199].

[13] Janssen v Juno [207].

[14] Biogen [139].

[15] Regeneron [171].

[16] Janssen v Juno [101], [202].

[17] Janssen v Juno [129].

[18] Janssen v Juno [140].

[19] Janssen v Juno [202].

[20] Janssen v Juno [208].

[21] AstraZeneca v Pharmacor [51].

[22] AstraZeneca v Pharmacor [69].

[23] AstraZeneca v Pharmacor [76].

[24] AstraZeneca v Pharmacor [110].

[25] AstraZeneca v Pharmacor [109].