38 U.S.C. § 1173

1. (a)The Secretary shall establish a process to conduct a formal evaluation with respect to each recommendation made by the Working Group under section 1172 of this title.
2. (b)The Secretary shall ensure that each formal evaluation under subsection (a) covers the following:
   1. (1)Scientific evidence, based on the review of available scientific literature, including human, toxicological, animal, and methodological studies, and other factors.
   2. (2)Claims data, based on the review of claim rate, grant rate, and service connection prevalence, and other factors.
   3. (3)Other factors the Secretary determines appropriate, such as—
      1. (A)the level of disability and mortality caused by the health effects related to the case of toxic exposure being evaluated;
      2. (B)the quantity and quality of the information available and reviewed;
      3. (C)the feasibility of and period for generating relevant information and evidence;
      4. (D)whether such health effects are combat- or deployment-related;
      5. (E)the ubiquity or rarity of the health effects; and
      6. (F)any time frame during which a health effect must become manifest.
3. (c)
   1. (1)The Secretary shall ensure that each formal evaluation under subsection (a)—
      1. (A)reviews scientific evidence in a manner that—
         1. (i)conforms to principles of scientific and data integrity;
         2. (ii)is free from suppression or distortion of scientific or technological findings, data, information, conclusions, or technical results; and
      2. (B)
         1. (i)evaluates the likelihood that a positive association exists between an illness and a toxic exposure while serving in the active military, naval, air, or space service; and
         2. (ii)assesses the toxic exposures and illnesses and determines whether the evidence supports a finding of a positive association between the toxic exposure and the illness.
   2. (2)In carrying out paragraph (1)(B)(ii), a formal evaluation under subsection (a) shall include reviewing all relevant data to determine the strength of evidence for a positive association based on the following four categories:
      1. (A)The “sufficient” category, where the evidence is sufficient to conclude that a positive association exists.
      2. (B)The “equipoise and above” category, where the evidence is sufficient to conclude that a positive association is at least as likely as not, but not sufficient to conclude that a positive association exists.
      3. (C)The “below equipoise” category, where the evidence is not sufficient to conclude that a positive association is at least as likely as not, or is not sufficient to make a scientifically informed judgment.
      4. (D)The “against” category, where the evidence suggests the lack of a positive association.
4. (d)Not later than 120 days after the date on which a formal evaluation is commenced, the element of the Department that conducts the evaluation shall submit to the Secretary a recommendation with respect to establishing a presumption of service connection for the toxic exposure and illness, or modifying an existing presumption of service connection, covered by the evaluation.