improvements in quality or more effective compensation of injured persons. In addition, tort reform discussions in most states have largely been around competing views from organized medical groups and trial lawyers and have not directly involved proponents of the quality improvement and error reduction position. Expanding Risk Pools. Since medical malpractice has developed on a state-by-state basis, the insurance coverage for malpractice has reflected the differences among the states. In many states, the majority or all of the malpractice insurance is provided through companies owned by the medical association or other physician groups. Many large hospitals and physician groups are self-insured, meaning they pay their own malpractice expenses up to a certain limit and only buy what is know as re-insurance to cover losses above that point. Even when an insurance company sells malpractice insurance in multiple states, premiums are still based on the expected experience of physicians within a single state or an even smaller geographic area. As a result, the differences in medical malpractice law among the states can lead to substantial differences in the cost of malpractice insurance from one state to another, even for the same specialty, and to wide fluctuations from year to year. 15 No measures that would broaden and thereby stabilize physician risk pools have been identified. Prudent Physician Standard of Care. As noted above, the performance standard physicians are held to has largely moved from a local to a national one. In either case, the standard of care was still based on what other physicians would consider accepted medical practice. Some courts, however, have held physicians to a standard that reflects what was possible, given the state of medical science and technology, even if very few or even no physicians actually practiced at that level. The first notable case to follow this approach was some thirty years ago,21 but in the intervening years there have been very few other cases that did so. Only a few courts have imposed this approach, which considers that physicians are not being reasonably prudent in delivering care if they simply practice in the accepted way when better care is possible. This potential shift in expectations, and the increased likelihood of being found negligent, has emerged as a serious concern for physicians, but has not taken widespread hold as a statutory reform. Enterprise Liability. The Clinton health reform proposal in 1993 included a number of the malpractice reforms outlined above. The most far-reaching and contested proposal was one that was considered during the planning stages but did not appear in the final legislation. That malpractice reform would have shifted liability from physicians to health plans and other enterprises, an approach known as “enterprise liability.” This approach was consistent with the direction of the Clinton plan, under which physicians and other providers were to be affiliated with only one or a few health plans. It is not as easily applied under the current structure of our health care system, since physicians may have many such affiliations, or they may have no managed care contracts at all. Enterprise liability has received some attention in the academic literature, but has not been enacted as such thus far. Some states have attempted to hold health plans accountable for harm that results when the plan in effect makes “medical decisions,” but those laws do not shift liability away from the physician who acts negligently. 21 Helling v. Carey, Supreme Court of Washington, 83 Wn.2d 514; 519 P.2d 981, 1974. 16 Trends in Medical Malpractice Claims and Payments This section presents trend data nationally and for states on the number of malpractice claims and average and total claims costs. Getting comprehensive data on medical malpractice trends in the United States is a challenging task because most claims tracking systems are maintained by individual states or private insurance companies, and confidentiality provisions severely limit access to these data. We rely on two different data sources to provide information on U.S. trends. The first source – the National Practitioner Data Bank (NPDB) – is a national database maintained by the Health Resources and Services Administration (HRSA) in the federal Department of Health and Human Services. The NPDB was mandated in 1986 22 and began collecting data on September 1, 1991. Since its inception, the NPDB has accumulated data on approximately 200,000 medical malpractice payments made on behalf of physicians. The second source – the Physician Insurers Association of America’s (PIAA) Data Sharing Project – is a private database maintained by PIAA for the purpose of tracking industry trends. PIAA data are used primarily by insurance company members of PIAA to examine trends in the medical conditions, procedures, and practices that give rise to medical malpractice claims.23 This database can provide more detail than NPDB data, but on a more limited set of claims and physicians. While each of these data sources has limitations, analyses of these data provide important insights concerning recent trends in medical malpractice claims and payment rates.24 22 Title IV of P.L. 99-660, the Health Care Quality Improvement Act of 1986, as amended. 23 Smarr LE. A Comparative Assessment of