Tuesday, 23 June 2015

The expert witnesses (2)

Should history every allow for Justice Riordan to talk about his ruling on the Blais-Létourneau class action trials, I would not be surprised to hear him identify the use of epidemiology as the "landmark" in this landmark trial.

Epidemiologists (like judges in a class action) look at the shared and often common health circumstances of a group of individuals. This is different than a clinical approach (or an individual trial) where the focus is on individualistic and often distinctive health circumstances.

From early in the trial, Justice Riordan resisted efforts to have the court examine the circumstances of a sample group of individuals. His reasons were re-stated in his final ruling:
"We have repeatedly held that, in class actions of this nature, the usefulness of individual testimony is inversely proportional to the number of people in the class. As we shall see, the number of people in the Classes here varies from 100,000 to 1,000,000. These proportions render individual testimony useless..." **
Justice Riordan made clear that it was the testimony of experts which would inform his decisions about the harms experienced by Quebec smokers. There were no experts in this trial whose views were more crucial to the outcome of this trial than the epidemiologists, statisticians and physicians who testified.

The epidemiologists and disease experts

On behalf of the plaintiffs in the Blais case, the court was presented with the views of (left to right) epidemiologist Jack Siemiatycki, otorhinolaryngologist Louis Guertin, and lung specialist Alain Desjardins.

Jack Siemiatycki supported the plaintiffs' position that it was appropriate to consider that smokers who suffered from the diseases in question were more likely than not to have become ill as a result of smoking.

Drs. Guertin and Desjardin testified about the link  between smoking and disease, and also the suffering that was experienced as a result of these cancers and emphysema. (The issue of suffering was not one that was contested).

The defence focused their efforts on attacking the evidence of Jack Siemiatycki about how to decide whether any specific individual's disease was caused by smoking. Their goal seemingly was to convince this court (or the appeal courts that will later review evidence in this trial) that such an approach was neither solid nor appropriate. Their arguments all supported the need for individual assessments of each smokers' circumstances. (Shades of Howard Engle?)

To support this position, they brought four experts to court: (left to right) statisticians Bertram Price and Laurentius Marais, epidemiologist Kenneth Mundt, and pathologist Sanford Barsky.

 The "novel approach" of Jack Siemiatycki.

In his efforts to estimate how many class diseases were 'more likely than not' to have been caused by smoking, Montreal epidemiologist Jack Siemiatycki setttled on the idea of a pack-year threshold. (Each pack year represents 7,3000 cigarettes smoked - or one package per day per year).

Those who had smoked more than 5 pack years had a more than doubled risk of lung cancer, he said. Their cancer could therefore be considered more likely than not to have been caused by smoking. Mid-trial, Justice Riordan accepted this critical-dose threshold as the basis for a redefinition of who would be included in the class action.

This, it would appear, is a new way of proving things in court. As Justice Riordan explains:
This was indeed a unique approach to determining causation. No expert that testified in this proceeding, including Siemiatycki, identified any other instance in which epidemiology had been used to establish a threshold number of lifetime cigarettes smoked that would allow one to conclude that a disease case in an individual was caused by smoking.

When later publishing his work in the American Journal of Public Health, Mr. Siemiatycki himself described his method as a "novel approach".

It's never easy to be first. As might be expected for any "novel" legal approach, the critical-dose method to establish causation came in for extensive criticism from the defendants' lawyers and their experts.

This will likely be the centrepiece in the appeals that the companies will launch later this week. No surprise, then, that in his ruling, the judge gave the Appeal Courts a full explanation of why he relied so heavily on Mr. Siemiatycki and why he chose to reject the experts who challenged this method.

The "most credible and convincing witness" and those who weren't allowed to be

No other expert received the level of praise that was directed at Mr. Siemiatycki. Justice Riordan identified him as a "highly-respected member of the world scientific community" with long experience in studying the impact of tobacco on the health of Quebecers.

The judge found that this witness' willingness to err on the side of caution, and to be "unafraid to admit weaknesses that might exist" made him who "fulfilled the expert's mission perfectly." 

By contrast, he found the experts offered by the companies failed to respect their responsibilities to "enlighten the court... objectively, impartially and thoroughly".  He did not criticize the skills or knowledge of these experts, and instead laid the blame with the way the defence lawyers managed their witnesses:
"The Court would have welcomed any assistance that the Companies' experts could have provided on this critical question, but they were almost always compelled by the scope of their mandates to keep their comments on a purely theoretical or academic level, never to dirty their hands with the actual facts of these cases."
"the Companies, who religiously refrain from allowing their experts to offer their own views on medical causation between smoking and the Diseases." ...
"the companies did not allow their experts even to try to make such evidence." 
"the Companies studiously avoided dealing with the base issue of the amount of smoking required to cause a Disease. Their strategy with almost all of  their experts was to criticize the Plaintiffs' experts' proof while obstinately refusing to make any of their own on the key issues facing the Court, e.g., how much smoking is required before one can conclude that a smoker's Disease is caused by his smoking. The Court finds this unfortunate and inappropriate."
It is not enough to criticize

In his ruling, Justice Riordan repeated the views he had expressed during the testimony of these experts. It was not enough for them to criticize the methods used by Jack Siemiatycki - they were expected to support an alternative answer --- to give "proof of a different reality." 

Without this, the judge had only one option before him. How the companies would have answered the epidemiological questions was a "page ... left blank" "Thus, the Court will never know how, or if, their opinions would have changed had they applied their expertise to the actual legal situation in place. 

He essentially disqualified the contribution of the defence experts. "...the Court finds no use for Dr. Marais's evidence." "...the Court finds no use for Dr. Price's evidence."

Most of the testimony of Drs. Barsky and Mundt was similarly rejected - except where they agreed to the idea that pack-years were a valid assessment of risk.

Defence epidemiologist Dr. Mundt had said there was "little or no risk of lung cancer below 10 to 15 pack years," so the judge raised the smoking threshold for eligibility in the Blais class from 5 to 12 pack years. Now, in order to qualify as a member of the Blais class, one must have smoked 87,600 cigarettes before November 20, 1998 and have been diagnosed with one of the specified diseases before March 12, 2012.


**This approach was given a boost in 2009 when the Quebec legislature passed the Tobacco-related Damages and Health Care Costs Recovery Act (TDRA). Article 15 of that law directs the court to allow statistical evidence in tobacco class actions.

But well before that green light, this trial was headed in that direction. Even before the TDRA was introduced to the legislature, Justice Riordan had ruled in favour of an epidemiological approach. And epidemiologist Jack Siemiatycki's expert report for the plaintiffs, which would have been in the works for months previously, was filed in the same month that the law was adopted.