Beginning with the early colonial settlements of America, the nation has provided benefits in varying degrees to those who have worn the uniform and suffered physical disabilities in service to the nation—sacrifices that are inherent to the profession of arms. In 1718, for instance, the colony of Rhode Island enacted legislation that provided benefits not only to every officer, soldier, or sailor who served in the colony's armed services, but also to the wives, children, parents, and other relations who had been dependent upon a slain servicemember. "The physically disabled were to have their wounds carefully tended and healed at the colony's expense, while at the same time an annual pension was provided to him out of the general treasury sufficient for the maintenance of himself and family, or other dependent relatives." These benefits were continued by the Continental Congress, which passed a resolution on August 26, 1776, providing for disabled veterans to receive half of their monthly pay for life or for as long as their disability existed. From the Revolutionary War to the current conflicts in Afghanistan, Iraq, and elsewhere, as the nature of the nation's wars has evolved, and as the needs of each generation of veterans who fought those wars have changed, Congress has debated, legislated, and revised benefits provided to veterans. In general, veterans are eligible for disability compensation if it can be demonstrated that the disabling condition or illness is linked to military service. Veterans could meet the burden of proving that their disabilities were service-connected through their military records, which may clearly describe and document the circumstances and medical treatment for an injury or an illness incurred while in service as well as any resulting disability. However, where the manifestation of the disabling disease or condition is remote from the veteran's service and any relation between the disability and service is not readily apparent, the burden of proving service connection can be a challenge. In such circumstances, Congress and the Department of Veterans Affairs (VA) have relied on presumptions to ease the burden placed on the veteran. Since the early 1920s, almost every Congress has examined the issue of whether one may presume that a veteran's disability is service-connected when there is no clear evidence to establish an illness or disability is caused or aggravated by a veteran's military service. More recently, Congress and the VA have relied on scientific evidence to establish presumptions. However, when the scientific evidence is incomplete and there is uncertainty on the question of causation or if other factors such as natural aging could also contribute to disease causation, Congress and the VA are faced with the challenge of instituting a transparent and equitable process to establish presumptions to compensate veterans for service-connected conditions. In the early 1990's at the request of the then Chairman of the Senate Committee on Veterans' Affairs, the VA prepared an analysis tracing the historical development of presumptions of service connection. More recently, at the request of the Veterans' Disability Benefits Commission, the Institute of Medicine (IOM) of the National Academy of Sciences (NAS) did a comprehensive study evaluating the presumptive disability decision-making process, which was released in 2008. Much of the interest with presumptions has focused on Vietnam veterans' exposure to Agent Orange and its contaminant dioxin. The Veterans' Disability Benefits Commission, in its task assignment to IOM, raised some potential issues with the current process of making presumptions: Certain studies (not even necessarily involving veterans), for example, showing that those exposed to [Agent Orange] dioxin have slightly higher rates of diabetes or prostate cancer, have resulted in an inexorable push to compensate all veterans with diabetes/prostate cancer even if it is likely that [Agent Orange] dioxin exposure is a determinative factor in only a small percentage of cases. Since it is impossible to know what role dioxin played in any particular case, all Vietnam veterans with diabetes and prostate cancer have been and are being granted presumptive service connection. Is this presumption fully supported by medical evidence? What amount of increase in occurrence rate is enough to warrant compensation? What approaches could be considered to alleviate this costly result? The purpose of this report is to examine the very complex and sometimes controversial policy issue of establishing presumptive service connection. The material in it is based in large part on VA's "Analysis of Presumptions of Service Connection," and IOM's "Improving the Presumptive Disability Decision-Making Process for Veterans" reports. In order to provide some context to the discussion of presumptions, the first part of this report briefly discusses disability compensation and the establishment of service connection for veterans claiming disability compensation. The second part provides an overview of the legislative history of establishing presumptive service connection. Since most of the controversy about establishing presumptions of service connection is related to exposure to Agent Orange, the third part of this report examines the establishment of presumptions for conditions related to Agent Orange. This part also provides a historical overview leading up to the passage of the Agent Orange Act of 1991 ( P.L. 102-4 ). The fourth part of the report discusses the passage of the Agent Orange Act, which set forth the current process for establishing presumptions. Lastly, it briefly discusses some options that may assist policy makers in their deliberations to make the presumptive decision-making process more transparent and equitable. The purpose of disability compensation is to assist currently disabled veterans whose injuries are connected to military service Although a veteran may have been ill or sustained an injury while in service, the mere fact that this occurred is not compensable. It should also be noted that not all persons who served in the military are considered veterans for purposes of veterans benefits. Currently, there are five ways to establish that a disability is service-connected: 1. Through direct service connection—that is, the facts, shown by evidence, establish that a particular injury or disease resulting in a disability was incurred while in service in the Armed Forces; 2. Through aggravation during service—that is, a preexisting injury or disease will be considered to have been aggravated while in service in the Armed Forces; 3. Through proximity—that is, a disability, which is proximately due to, or the result of a service-connected disease or injury which is itself considered to be service-connected. An example would be a veteran developing cardiovascular disease due to a service-connected amputation of a lower limb. 4. Through a finding that the disability was caused by medical care or vocational rehabilitation provided by the Department of Veterans Affairs (VA)—disabilities caused by VA provided medical care or vocational rehabilitation are treated as if they are service-connected. 5. Through the application of statutory presumptions—that is, certain diseases as established by law or regulation are considered to have been incurred in or aggravated by service in the Armed Forces even though there is no evidence of such disease during the period of service. VA has the authority to provide disability compensation to veterans by bypassing the first four criteria. The next section discusses what a presumption is, and provides a brief legislative history of establishing presumptive service connection. In the context of VA claims adjudication, a presumption relieves veterans of the burden to prove that a disability or illness was caused by a specific exposure that occurred during service in the Armed Forces. When a disease is designated as presumptively service-connected, the individual veteran does not need to prove that the disease was incurred during service. In other words, a presumption shifts the burden of proof concerning whether a disease or disability was caused or aggravated due to service from the veteran to the VA. The VA would have to demonstrate that some other intervening event caused the disability in order to rebut the presumption. Often presumptions are applied to chronic diseases or illnesses that manifest after a period of time (sometimes many years) following service, and that may also occur in individuals who have never served. According to the VA's Analysis of Presumptions of Service Connection: Generally, a legal presumption is a procedural device that shifts the burden of proof by attaching certain consequences to the establishment of certain basic evidentiary facts. When the party invoking a presumption establishes the basic fact(s) giving rise to the presumption, the burden of proof shifts to the other party to prove nonexistence of the presumed fact. A presumption, as used in the law of evidence, is a direction that if fact A (e.g., manifestation within the specified period of a disease for which a presumption of service connection is available) is established, then fact B (service connection) may be taken as established, even where there is no specific evidence proving fact B (i.e., no medical evidence of a connection between the veteran's disease and the veteran's military service). The legislative history of veterans' disease presumptions dates back to 1921 when Congress, to ease the decision-making process in VA disability compensation adjudications, used its authority to establish service connection on a presumptive basis. Below is a synopsis of major legislation. The first legislation that specifically established a presumption of service connection was the amendment of August 9, 1921, (P.L. 67-47) to the War Risk Insurance Act (P.L. 63-193). This amendment, among other things, established presumptions of service connection for active pulmonary tuberculosis and neuropsychiatric disease (later known as psychosis) occurring within two years of separation from active duty military service. Prior to the passage of P.L. 67-47, disability compensation for World War I veterans was payable only for a disability directly related to military service. Broadly, the intent of this liberalization legislation was that "as the period beginning with the end of the war lengthened it became increasingly difficult to establish service connection for some ailments, particularly tuberculosis and neuropsychiatric disease." The amendments to the War Risk Insurance Act also gave the then Veterans Bureau authority to establish rules and regulations to carry out provisions in the act. This allowed the agency to promulgate regulations establishing presumption of service connection for certain diseases. As stated in VA's Analysis of Presumptions of Service Connection: Regulation No.