Standards of Proof
Although there is always room for interpretation, there are
three main standards of proof that various statutes can and do prescribe:
- Possibly. Since it is only necessary to show that there is some credible evidence that something might be true, this is a very weak standard.
- As Likely As Not. Also known as preponderance of the evidence, this standard requires that that the evidence FOR outweigh that AGAINST by at least some slim margin. This is the standard typically employed in civil cases.
- Almost Certainly. Criminal proceedings that require proof of guilt employ the beyond a reasonable doubt standard.
Food Law Interpretation
The premarket approval clauses of the Federal Food Drug and
Cosmetic Act (sections 408 and 409) clearly operate with a standard of proof
that corresponds to “Possibly”. If there
is some reasonable possibility of harm then an additive or pesticide is not
safe. The “reasonable certainty of no
harm” provision of the Toxic Substances Control Act is of the same ilk.
There has always been an inclination to evaluate
contaminants in the same way as additives.
For example, Hutt (1978) wrote:
Some have suggested that different
rules should apply with respect to environmental contaminants (such as
aflatoxin in peanuts) as contrasted with substances used in the production of
food (for example packaging materials) or direct food ingredients (such as
saccharin). There is, however, no
conceptual or rational basis for this distinction. An environmental contaminant can be reduced
or eliminated from the food supply just as easily as an indirect constituent or
a direct ingredient.
Hutt was simply wrong about this. First of all, there clearly IS a conceptual
basis for treating contaminants differently because the legal statutes pertaining
to their regulation are quite different.
Second, there is a rational basis as well. It seems obvious that eliminating an
artificial sweetener with no nutritive value will not diminish the supply of
food. On the other hand, eliminating
peanuts will. So, a chemical may be
“tolerable” as a contaminant even if it is not “acceptable” as an
additive.
The standard of proof that underlies the older provisions
(sections 402 and 406) that still pertain to contaminants are not as clear
cut. However, there is no reason to
suppose that “some credible evidence” is the operating standard. In fact, the FDA has gone to court with that
stance many times and lost. Even though
the food industry can be expected to claim that “beyond a reasonable doubt” is
required, when and insofar as I was the agency, I always thought “as likely as
not” was a very fair standard. But, I
never went to court with it. Regarding
402(a)(1), the other issue that is sometimes troublesome lies in determining what
constitutes an “injury”.
Quantitative Interpretations
Translating scientific evidence into legal evidence often
requires matching legal standards of proof to quantitative characterizations of
probability. The most straightforward
example of this is the use statistical characterizations of uncertainty to
decide a toxic tort case where the operating standard is preponderance of the
evidence (Black and Lilienfeld, 1984).
If there is a greater than 50% chance that a chemical produced by the
defendant caused a disease suffered by the plaintiff then the plaintiff
wins. For most other legal standards
there is no established quantitative equivalency. However, there is strong tendency to equate a
probability of 95% with beyond a reasonable doubt, while a probability of 5% is
sufficient for a reasonable possibility.
For example, while a NOAEL determination typically uses a 95% threshold
to determine whether or not an effect has been observed, and BMDL uses a 5%
threshold to determine that particular effect may occur.
The other issue that must be confronted when supplying a quantitative
argument for legal or public policy is that the probability in need of quantification
often does not have a statistical origin.
This is especially likely to happen with small theoretical risks that
cannot be measured with any precision.
Probability trees may be used for this purpose (e.g. Morgan et al, 1980; Evans, et al, 1994; Carrington et
al, 2013). Since assigning
probabilities to theories is subjective, at least in part, using probability
trees never makes anyone very comfortable, which has undoubtedly limited their
use. Nonetheless, for contentious
scientific issues, probability trees are a very useful tool for separating
scientific opinion from political opinion.
Judges and Peers
In the courtroom and in public policy, the determination of matters
of fact involving scientific issues often defer, at least in part, to expert
opinion. Agency documents that contain influential
information are routine subject to interagency review and may also be required
to be subjected to nongovernmental peer review as well. There are, of course, scientific
disagreements. But, in addition, different
agencies, different programs within the same agency, and different academic
professions often employ different standards of proof. In a courtroom, those issues are resolved by
the law and the court. In a public
policy debate, there often is no mechanism for adjudicating exactly what the standard
of proof is. For example, I think “as-likely-as-not”
is a good general purpose standard, but not everyone agrees.
Reviewers with an academic perspective are especially apt to
think that the standard of proof enforced within their discipline is the only
standard there is. That goes double or
triple for academic disciplines that are strongly associated with public policy
like toxicology and nutrition. In fact,
there is a tendency to equate public policy standards with the standards used
for publication in academic journals.
That can be disastrous. The biggest
problem is that environmental toxicologists generally look at all chemicals
with premarket approval lenses. As a
result, they try to use and impose a standard of proof that is really quite weak, which
is especially inappropriate when the government is responsible for building a case
(e.g. for 402 or 406). Another common
problem that arises is when it is necessary to balance toxicological risks
against nutritional risks (e.g. Olin, 1998; FDA, 2014). Whereas toxicologists often insist on a very
weak standard of proof, nutritionists are inclined to want one that is far closer
to certainty. Even though they may not
agree on the standard of proof at all, both toxicologists and nutritionists may still agree that a quantitative analysis that uses as-likely-as-not standard to
identify an optimum is an affront to their academic sovereignty.
References
Black B and Lilienfeld DE (1984). Epidemiologic Proof in Toxic Tort Litigation. Fordham
Law Review 52:Issue 5, Article 2.
Carrington CD, Murray C, and Tao, S. (2013). A
Quantitative Assessment of Inorganic Arsenic in Apple Juice.
Evans, J.S., Graham, J.D., Gray, G.M., and Sielken, R.L.,
Jr. (1994). A distributional approach to
characterizing low-dose cancer risk. Risk Anal 14: 25-34.
Hutt PB (1978).
Unresolved Issues in the Conflict Between Individual Freedom and
Government Control of Food Safety. Food Drug Cosmetic Law Journal 33:558-589.
Morgan MG, Morris SC, Amral DAL, and Rish WR (1984). Technical Uncertainty in Quantitative Policy
Analysis – A Sulfur Air Pollution Example.
Risk Anal 4:201-230.
Olin, SS (1998).
Between a Rock and a Hard Place: methods for Setting Dietary Allowances
and Exposure Limits for Essential Minerals.
J. Nutr. 128:364S-367S.
U.S. Food and Drug Administration (2014). Quantitative
Assessment of the Net Effects on Fetal Neurodevelopment from Eating Commercial
Fish (As Measured by IQ and also by Early Age Verbal Development in Children).
Official Post Soundtrack
Post Notes
Thesis Post #35. Back on the Regulatory Toxicology thread.
No comments:
Post a Comment