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The Defendants, Boston Scientific Ltd. and Boston Scientific Corporation (collectively “Boston Scientific”) designed, manufactured and sold transvaginal mesh (“TVM”) medical devices that were implanted into thousands of Canadian women for the treatment of Stress Urinary Incontinence (“SUI”) and Pelvic Organ Prolapse (“POP”).

SUI is the involuntary leakage of urine on effort or exertion, such as sneezing, coughing, or laughing. POP is the downward descent of female pelvic organs, including the bladder, bowel and uterus, occurring over time as vaginal muscles weaken and lose their ability to offer support.

The Plaintiffs, Ms. Vester and her husband, commenced a proposed class action under Ontario’s Class Proceedings Act, 1992, S.O. 1992, c 6 (the “CPA”), alleging that the devices are defective and unsafe and can cause serious and sometimes permanent complications. They further allege that the Defendant failed to properly warn of the complications and the long term implications of mesh implantation, through the products’ Directions for Use or “DFUs.” The Vesters sought to have their action certified as a class action.

The motion was heard by Justice Perell of the Ontario Superior Court of Justice. Although, based on the Plaintiffs’ evidence, Justice Perell appreciated that the TVM devices at issue shared common features, (for example, all of the devices at issue are made out of the same type of Type I polypropylene made from HGX-0301-01 polypropylene resin, and are all used for urogynecological procedures), given that Boston Scientific manufactured different types of TVM devices, Justice Perell was of the view that in order to certify the action, he required evidence identifying the specific common defect being alleged by the Plaintiffs.

In December, 2015, Justice Perell released his decision, adjourning the certification motion to permit the Vesters to provide further evidence to establish some-basis-in-fact for common issues for the negligent design claim or for the failure to warn claim, and to establish that a class action would be the preferable procedure for the determination of those common issues.

Resumption of the certification motion

After the adjournment of the 2015 certification hearing, the Vesters served three additional expert reports: (a) the report of Dr. Scott Guelcher, Ph.D. a chemical engineer, (b) the report of Dr. Vladimir Iakovlev, M.D., an anatomical pathologist, and (c) the report of Dr. Cheryl Blume, Ph.D, president of a consulting firm specializing in pharmaceuticals, medical devices and healthcare products. Boston Scientific responded with additional evidence: (a) the report of Dr. Stephen Badylak, an anatomic pathologist; (b) the evidence of Dan Krause, Manager of Regulatory Affairs for Boston Scientific and (c) the report of Dr. Michael Duoso, an urogynaecologist.

Unlike the first attendance, when the certification motion resumed, Justice Perell found that the Vesters had identified the manufacturing defect in Boston Scientific’s transvaginal mesh products, having specified what is wrong with the design. The Plaintiffs had shown that there is some basis in fact that the use of HGX-030-01 polypropylene makes a transvaginal mesh product defective, such that the design of Boston Scientific’s SUI and POP products is negligent. In this regard, the Plaintiffs had provided further evidence of clinically significant implications to women with mesh implants, as a result of the propensity of the polypropylene mesh to degrade in the body. Similarly, the Plaintiffs established some-basis-in-fact for duty to warn common issues, having identified the alleged inadequacy in the DFUs to address both the permanency of the mesh, and the potential for mesh complications to be permanent.


The Defendants’ arguments that there was no evidence that the degradation in the polypropylene has clinical significance in a patient in whom the transvaginal mesh device is implanted – in part, because the alleged material changes were microscopic – were rejected by Justice Perell. The evidence presented by the Plaintiffs, through Drs Guelcher and Iakovlev, provided some-basis-in-fact that the polypropylene degraded and that the degradation had clinical significance, and provided a theory of how the degradation could cause harm. As found by Justice Perell, although the truth of such evidence may be ultimately refuted, the skepticism of the Defendants’ experts was not sufficient to have established that there was no basis-in-fact for the common issues. Section 5(5) of the CPA provides that an order certifying a class proceeding is not a determination of the merits of the proceeding.

Although the Defendants argued that the Plaintiffs had not put forward an appropriate methodology or design alternative, Justice Perell found these arguments to be merits based. He further found that if the court determines that the microscopic degradation of the polypropylene does not occur in the body, or that if it occurs, it has no clinical significance, then there will be a common answer to all of the Class Members’ claims. Likewise, if the court determines absolutely or in a nuanced way that: the microscopic degradation of the polypropylene does occur in the body; the degradation has clinical significance; and Boston Scientific, by choosing HGX-030-01 polypropylene in design its medical devices for implanting in women’s bodies did not meet the standard of care, then there will be a common answer to the common question. In either event of the outcome of the common issues, there are productive common issues that justify certifying the Vesters’ action as a class proceeding.

The Vesters’ action was certified as a class proceeding.


Despite the fact that the court has authority under section 5(4) of the CPA to adjourn the motion for certification to permit the parties to amend their materials or pleadings or to permit further evidence, such discretion is not often exercised by the court where it is found that commonality is lacking for the proposed common issues. In the parallel mesh action against Bard,[1] for example, Justice Perell declined to certify the action, finding that a discrete product-by-product risk-benefit analysis would be required in that case as there were many different devices, and that was therefore no commonality of causation just from the fact that the action as it was structured was “all about the mesh.” In O’Brien, Justice Perell noted that although he had the jurisdiction to adjourn Ms. O’Brien’s certification motion to permit her to amend her materials or pleadings to permit further evidence, he afforded her the opportunity, pursuant to section 7 of the Class Proceedings Act, 1992, to attempt to certify a smaller proposed class action.

This trend is likely because the decision to certify is not merits-based. The certification test must be applied in a purposive and generous manner, to give effect to the important goals of class actions – providing access to justice for litigants; promoting the efficient use of judicial resources; and sanctioning wrongdoers and encouraging them to modify their behaviour.[2] The certification test does not ordinarily require the high level of evidence provided by the Plaintiffs at the second certification attendance, as such is a further descent into the merits of the Plaintiffs claims than is required to satisfy the some-basis-in-fact criteria of the commonality requirement. Unlike O’Brien, the evidence presented at certification in the Vester action established that all nine of Boston Scientific mesh devices were made of the same Type I polypropylene, regardless of the design of the mesh device, or the urogynecologic purpose for which it was implanted. On this basis, it was argued that there was sufficient commonality to support certification.

The Courts have held that although certification will be denied if there is an insufficient evidentiary basis for the facts on which the claims of the class members depend,[3] the some-basis-in-fact test sets a low evidentiary standard for plaintiffs.[4] As a general rule, the some-basis-in-fact test must not lead to an assessment of the contested facts going to the merits of the case. At the first certification attendance, the Plaintiffs had put forward evidence of the propensity of polypropylene to cause complications, and of the commonality of the specific type of polypropylene used in Boston Scientific’s transvaginal mesh devices. Despite the evidence, Justice Perell noted that given the absence of identifying a specific design defect in using Type I polypropylene mesh for a TVM device, the fact that there were adverse consequences from the use of the Boston Scientific meshes did not provide sufficient some-basis-in-fact for concluding that there was a common issue relating to the standard of care with respect to the design issues raised by the Plaintiffs. It was not enough for the Plaintiffs to assert that the “mesh” itself was the problem.

Nevertheless, in this case, Justice Perell found, at the conclusion of the first certification attendance, that the pleadings disclosed a cause of action, that the proposed class definition satisfied the requirements of the CPA, and that, subject to further evidence establishing commonality, the Vesters might be appropriate representative plaintiffs. As a result, Justice Perell was of the opinion that the Vesters’ case was an appropriate one for an adjournment to permit them to specify what, precisely is wrong with the polypropylene mesh in each of Boston Scientific’s nine products, and to specify what is the failure to warn for each of the nine products.

[1] O’Brien v. Bard, 2015 ONSC 2470 (CanLII)

[2] Martin v. Astrazeneca at para. 96; Western Canadian Shopping Centres Inc. v. Dutton, 2001 SCC 46 (CanLII), [2001] 2 S.C.R. 534 at paras. 26-29 (“Western Canadian Shopping”); Hollick at para. 15.

[3] Dumoulin v. Ontario, [2005] O.J. No. 3961 at para. 25 (S.C.J.); Fresco v. Canadian Imperial Bank of Commerce, [2009] O.J. No. 2531 at para. 21 (S.C.J.); Singer v. Schering-Plough Canada Inc., 2010 ONSC 42 (CanLII) at para. 140.

[4] Pro-Sys Consultants v. Microsoft, supra; McCracken v. CNR Co., 2012 ONCA 445 (CanLII).

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