Litigating the Alleged Carcinogenicity of Glyphosate in Monsanto’s Roundup: The Fairness (and Unfairness) of Deciding Causation Independent of Liability

January 17, 2019 by mjb443

By Leora Friedman, Staff Contributor.

The Northern District of California readies to hear the U.S.’s first federal test case regarding the carcinogenicity of Monsanto’s glyphosate-containing herbicide, Roundup. Controversially, in early January 2019, Judge Chhabria granted Monsanto’s request for bifurcation—agreeing first to litigate glyphosate’s causation to the plaintiff’s cancer and, only afterward, allowing evidence of Monsanto’s alleged efforts to sway agency positions on glyphosate. But can the reliability of scientific studies be determined without considering the institutions that may have housed and/or nurtured them?

Is glyphosate-containing Roundup, a Monsanto-produced herbicide,[1] fit for human use? Contradictory scientific analyses regarding the carcinogenic effect of the ingredient are now being tested in federal court, but the first three bellwether (test) trials will evaluate causation independent from allegations that Monsanto influenced agencies to assert glyphosate’s safety.[2] This court-ordered separation of issues is called bifurcation. While bifurcation may help untangle science from the alleged misconduct and institutional politics clouding the issue, it may detrimentally conceal any influences on evaluations of glyphosate that could otherwise illuminate their reliability.

Dewayne Johnson was the first plaintiff to argue the carcinogenicity of Roundup’s glyphosate in civil court[3]––and the first plaintiff to win.[4] In 2016, Johnson’s California-based products liability suit threatened Roundup’s status as the go-to weed killer for commercial farmers and suburban homeowners.[5] Johnson had been administering Roundup in a school district since 2012[6] and received a non-Hodgkin lymphoma diagnosis in 2014.[7] By arguing causation between his repeated exposure to glyphosate and his cancer, Johnson won his case.[8] Approximately 620 comparable cases now sit before Judge Chhabria in the Northern District of California.[9] But Johnson’s victory does not imply that future plaintiffs will enjoy similar results, as state decisions do not control in federal court.

Currently, Judge Chhabria is overseeing Hardeman v. Monsanto Co., the first bellwether trial.[10] As a test case, Hardeman can inform damages and settlement prospects for the other cases[11] whose pretrial proceedings were consolidated through multidistrict litigation (MDL) in In re: Roundup Products Liability Litigation.[12] In granting Monsanto’s bifurcation request on January 3, 2019, Judge Chhabria required the trial’s “first phase to address causation only and the second phase to address all remaining liability and damage issues.”[13] He reasoned that allegations that Monsanto “attempt[ed] to influence regulatory agencies and manipulate public opinion regarding glyphosate” pertain predominantly to punitive damages and liability and are a “a distraction” from the preliminary issue of causation between glyphosate and the plaintiff’s non-Hodgkin lymphoma.[14] These allegations ostensibly stem from the MDL litigants’ references to conflicting authorities; while the EPA wrote in December 2017 that “glyphosate is not likely to be carcinogenic to humans,” supporting Monsanto’s position,[15] the World Health Organization’s International Agency for Research on Cancer (IARC) indicated in March 2015 that glyphosate is “probably carcinogenic to humans,” supporting the plaintiffs’ position.[16] Perhaps, as Judge Chhabria suggests, a causation analysis should focus on underlying scientific data, not on an institution’s synthesis of the data in its messaging.

However, the bifurcation ordered in Hardeman—excluding evidence of either litigant’s endeavors “to influence regulatory agencies and manipulate public opinion”[17]—may inhibit the court from conducting a reliable causation analysis. First, the institutional context under which studies on glyphosate were conducted may expose an expert’s deliberate or negligent efforts to misrepresent or distort data. History has already witnessed an industry-driven coverup of tobacco’s inherent dangers.[18] For example, if Monsanto omitted self-damaging data regarding glyphosate in a mandated disclosure to the EPA, any EPA evaluations of glyphosate founded on that data would be based on incomplete information and, consequently, erroneous. Second, Judge Chhabria seeks to cure this deficiency by providing for the admissibility of “evidence that Monsanto manipulated the outcome of scientific studies, as opposed to agency decisions or public opinion regarding those studies.”[19] But conducting this inquiry each time Harbedon offers evidence of Monsanto’s alleged influence may prove inefficient or unfeasible, as the plaintiffs portend.[20] Moreover, a judge likely lacks the expertise and experience needed to decide whether a purported action by Monsanto could have “manipulated” the scientific results.[21]

On the other hand, the Daubert framework governing the admissibility of expert evidence in federal court offers an argument in support of bifurcation here.[22] In part, Daubert is concerned with the scientific community’s “acceptance” of “the reasoning or methodology” used to study glyphosate,[23] and it is unlikely that Monsanto influenced the community’s attitude toward a certain methodology even if it influenced perceptions toward glyphosate itself. Therefore, admitting evidence of this influence may spark more confusion than clarity with respect to causation.

A Daubert hearing is set for January 28, 2019.[24] You can stay up-to-date on developments through the Northern District of California’s webpage dedicated to the Roundup litigation:[25] Regardless of the outcome, hopefully future research will either confirm that glyphosate presents an unacceptable risk to consumers so the EPA can strictly regulate or ban it or, if glyphosate’s carcinogenic effect on humans proves negligible, free companies like Monsanto from undeserved impediments to growth.


[1] Roundup, Products, Monsanto, (last visited Jan. 11, 2019).

[2] See In Re: Roundup Products Liability Litigation, MDL No. 2741, Case No. 16-md-02741-VC (N.D. Cal. Jan. 3, 2019) (Pretrial Order No. 61 granting Monsanto’s request to bifurcate three bellwether trials).

[3] Carey Gillam, Landmark lawsuit claims Monsanto hid cancer danger of weedkiller for decades, Guardian (May 22, 2018),

[4] Emily Sullivan, Groundskeeper Accepts Reduced $78 Million Award In Monsanto Cancer Suit, NPR (Nov. 1, 2018),

[5] See generally Complaint for Damages and Demand for Jury Trial, Johnson v. Monsanto Co., No. CGC-16-550128, 2016 WL 347894 (Cal. Super. Ct. Jan. 28, 2016).

[6] Gillam, supra note 3.

[7] Complaint for Damages, supra note 5, at *11.

[8] Sullivan, supra note 4.

[9] Tina Bellon, U.S. judge stands by ruling to limit evidence in Roundup cancer trials, Reuters (Jan. 4, 2019),

[10] See Tina Bellon, U.S. judge selects first case in federal Monsanto weed-killer litigation, Reuters (Nov. 20, 2018),

[11] See id.

[12] See In re: Roundup Products Liability Litigation, 2014 F. Supp. 3d 1346, 1348 (J.P.M.L. 2016) (order consolidating “pretrial proceedings” and transferring to Northern District of California).

[13] See In Re: Roundup Products Liability Litigation, MDL No. 2741, Case No. 16-md-02741-VC (N.D. Cal. Jan. 3, 2019) (Pretrial Order No. 61 granting Monsanto’s request to bifurcate three bellwether trials).

[14] Id.

[15] EPA Releases Draft Risk Assessments for Glyphosate, EPA (Dec. 18, 2017),

[16] See IARC Monograph on Glyphosate, Int’l Agency for Res. on Cancer, World Health Org. (Jan. 3, 2018),

[17] In Re: Roundup Products Liability Litigation, MDL No. 2741, Case No. 16-md-02741-VC (N.D. Cal. Jan. 3, 2019) (Pretrial Order No. 61 granting Monsanto’s request to bifurcate three bellwether trials).

[18] Clay Calvert, Smoking Out Big Tobacco: Some Lessons About Academic Freedom, the World Wide Web, Media Conglomeration, and Public Service Pedagogy from the Battle Over the Brown & Williamson Documents, 24 Pepp. L. Rev. 391, 392 (1997).

[19] In Re: Roundup Products Liability Litigation, MDL No. 2741, Case No. 16-md-02741-VC (N.D. Cal. Jan. 3, 2019) (Pretrial Order No. 61 granting Monsanto’s request to bifurcate three bellwether trials).

[20] Id. (“Any such evidence will likely overlap with evidence of liability, but it will not be impossible, as the plaintiffs contend, to separate evidence of causation from evidence of liability.”).

[21] Id.

[22] See Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 594, 592-93 (1993).

[23] See id.

[24] In re: Roundup Products Liability Litigation (MDL No. 2741), U.S. District Ct. Northern District Cal., (last visited Jan. 11, 2019).

[25] Id.