Federal Court Appoints Assessor for Monsanto Class Action

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Roundup Herbicide by Monsanto

The Federal Court in McNickle v Huntsman Chemical Company Australia Pty Ltd (Assessors) [2021] FCA 780 (25 June 2021) recently decided to appoint an assessor to assist the court to understand  highly technical, and at times, conflicting, expert evidence. The arrangement signals a recognition by courts of the technical complexities of expert witness opinions, and the need for an assessor to assist.

Background and Summary 

The lead Applicant in the Monsanto Class Action had brought proceedings against Monsanto Australia, with claims that the company’s Roundup products (containing glyphosate) were carcinogenic, causing Non-Hodgkin’s Lymphoma in those exposed to the product. The Plaintiff Class alleged that Monsanto negligently sold the glyphosate products despite this knowledge.

Both parties produced expert evidence. The plaintiffs argued however that Monsanto’s evidence fundamentally lacked independence since the corporation had sponsored and manipulated the very scientific research publications and global regulatory reports it sought to rely on to conclude that Roundup Products did not cause cancer.

Both parties opposed the Court’s suggestion that it appoint its own referee or expert witness. Justice Lee agreed with the plaintiffs that the seriousness of the allegations, and the complexity of analysis required to address them, demanded open discussion between multiple experts. [Nickle v Huntsman Chemical Company Australia Pty Ltd (Expert Evidence) [2021] FCA 370 (11 March 2021), [4]-[7]).

The Court instead appointed an Assessor (as opposed to court-appointed witness) whose role the court saw as more appropriate for providing in-depth understanding and scrutiny of the issues, and therefore protection against more deeply-ingrained institutional bias in expert evidence. The application of the third person perspective and expertise of the Assessor ensures a degree of impartiality in the presentation of parties’ expert evidence not otherwise possible through more conventional procedural protections (e.g. those offered through expert conclaves and joint reports). [17] The decision demonstrates that courts are ever more willing to accommodate the increasing scale and technical specificity of expert evidence, particularly in Class Action matters. 

The Function of the Assessor

The Court emphasised that the role of the assessor would lie in their capacity to aid the court’s understanding of expert evidence rather than their power to evaluate the merits of evidence.

Although historically Courts of Admiralty have appointed ‘assessors’ as de facto expert witnesses, an assessor in the current matter would perform the role outlined by Justice Forrest in Matthews v SPI Electricity (Ruling No 32) [2013] VSC 630. In that case,the primary role of assessors is to assist the court in understanding the evidence of the experts”. The assessor’s role in that and the current matter includes:

  1. Notifying the judge of technical aspects of expert evidence that are unclear or incomplete;
  2. Providing suggestions to the judge for more appropriate or useful inquiries to make about the expert evidence;
  3. Advising the judge in chambers on any technical points on which the judge lacks knowledge and on technical issues the judge should resolve to determine the matter;
  4. Advising the judge on whether their judgement reflects a proper understanding of the expert evidence; and
  5. Advising the judge on disputes between expert witnesses, where the assessor’s advice is not binding.

The Power to Appoint

Justice Lee highlighted that the use by courts of “research staffs… to provide judges with specialised investigations, information and advice” [7] is historically not uncommon. Examples include the Jury of Merchants who advised the Court of King’s Bench on matters requiring attention to aspects of trade peculiar to merchants and the Court Referee or court-appointed expert witness.

The Court has power under Sections 23 and 33ZF of the Federal Court of Australia Act 1976 (Cth) to appoint an assessor for the matter. The implied power of the court to enact everything necessary to exercise its jurisdiction under that provision plainly includes the power to appoint an assessor.


  • Courts are able and willing to engage with increasingly more complex expert evidence. The appointment of an assessor to assist the court is likely to become a more common practice, particularly in class actions for industries in which sponsored research and publications abound.
  • The assessor in a matter will likely allow the court to evaluate evidence more thoroughly and with reference to experts’ citations of key publications.
  • Experts and lawyers on complex matters in which the court appoints an assessor, should take special care to be thorough and clear in their report writing.

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