TABLE 10 ESTIMATED NUMBERS OF DEATHS PER YEAR ASSOCIATED WITH OPERATION OF A 1000-MWe POWER PLANT INCLUDING ALL STAGES OF THE FUEL CYCLEа Stage in the Fuel Cycle aFrom Comar and Sagan, 1976; Keeny, et al, 1977; Cohen, et al, 1980; Cox, et al, 1983. bFigures, which are rounded, denote ranges of published values. CUpper values include allowances for consequences of major releases of radioactivity resulting from reactor core melt-down accidents (e. g., NRC, 1975). TABLE 11 COMPARATIVE ESTIMATES OF THE LIFETIME RISK OF RADIATION-INDUCED CANCER MORTALITYа The values are average values per rem, and are not to be taken as estimates at a dose of 1 rem only. 1972 BEIR postnatal, age-specific risk factors, used with 1969-1971 life tables, and with risk exending throughout the lifetime remaining after irradiation. Since the average age of the 1969-1971 life-table population exceeds that of the 1967 U.S. population used for the 1972 BEIR report, the numbers shown here for continuous exposure are larger, on a per-rem basis, than those in the 1972 BEIR report. dUNSCEAR range of estimates applicable to low-dose, low-LET radiation. PROOF OF CAUSATION THROUGH EXPERT OPINION EVIDENCE IN LOW-LEVEL RADIATION CASES Robert E. Heideck, Esq. Pepper, Hamilton & Scheetz April 1984 Copyright 1984 by American Nuclear Insurers Report to American Nuclear Insurers and I. PROOF OF CAUSATION THROUGH EXPERT OPINION EVIDENCE IN LOW-LEVEL RADIATION CASES INTRODUCTION Courts and boards charged with the duty of resolving claims for compensation are increasingly being confronted with claims by persons alleging that their cancers were caused by exposures to low-levels of radiation occurring many years before. In June 1979, for example, the Interagency Task Force on the Health Effects of Ionizing Radiation reported that between 1967 and 1979 the Veterans' Administration had decided 664 cases involving claims by veterans for diseases caused by alleged service-connected exposures to radiation.' That number has increased and promises to continue to increase. Court cases involving claims for cancer caused by exposures also promise to become more frequent.2 A major issue in such cases is whether the claimant can prove that the exposure to radiation was the legal cause of his injury. This paper describes briefly the expert testimony on the issue of causation which can be anticipated in a typical low-level radiation case, including evidence of the probability of causation, as well as some of the general legal standards imposed by the courts in admitting expert evidence. II. PROOF IN A TYPICAL TORT CASE A. Underlying Concept of the Tort System The tort system is not intended to be a pure no-fault compensation system for all injuries regardless of cause. Since it shifts the financial impact of loss from one person to another there must be sound justification. While in most cases this may be readily apparent, there are always legitimate threshold questions bearing on whether a particular individual claim merits compensation under tort law. B. Legal Standards of Causation and Proof In every personal injury case, the plaintiff must prove the existence of a causal relationship between the injury and some alleged wrongful act in order to be entitled to recover damages. The courts will not award compensation, for example, simply because an injury has occurred to some person who at one time was exposed to radiation.' Instead, the courts require that the claimant prove either that but for the exposure the cancer would not have occurred, or, at least, that the exposure was a substantial factor in causing the cancer. No matter how the test for legal causation is formulated by the particular jurisdiction, the requirement that the claimant prove causation is required by all, and this includes the production by the claimant of evidence that the exposure was, in fact, a cause of the injury. This part of the requirement of legal causation may be called proof of the "fact of causation”, and it is with respect to the proof of this element in low-level radiation cases that difficulties can be expected to arise.R 10 The burden placed upon the party seeking compensation for an injury in a civil case is that he prove all of the elements of his case, including "the fact of causation," by a "preponderance of the evidence." What this standard requires is that the quantum of proof offered by the plaintiff convince the finder-of-fact that the plaintiff's contention is more probably accurate and true than not accurate and true. And, in order to meet this standard, the plaintiff must offer competent evidence of record sufficient to support the conclusion that the defendant's conduct, more likely than not, caused the injury. Evidence which only shows a mere possibility of causation is not sufficient, and if the matter is one of pure speculation, or the probabilities at best are evenly balanced, the court should award judgment for the defendant." C. Expert Testimony Except in cases where there is an obvious causal relationship between the defendant's conduct and the alleged injury, expert testimony is required as evidence to prove causation. Given the nature of the claim for cancers allegedly caused by an exposure to radiation, especially an exposure to low-level radiation, it is expected that expert testimony will be required on the issue of causation. 12 The decision whether to admit expert evidence is one confined to the discretion of the trial court. In considering whether expert testimony should be admitted, the courts typically focus on two primary concerns. The first is whether the expert is qualified by education or experience to address the subject, or what is generally called |