The First Amendment of the U.S. Constitution provides the freedom to individuals to exercise their religious beliefs without governmental interference, and simultaneously prohibits government actions that benefit followers of one faith over another. At times, when government actions would otherwise burden individuals' religious exercise, the government makes efforts to accommodate the religious practice. However, accommodation of religion to prevent violations of the Free Exercise Clause must be carefully considered in order to prevent violation of the Establishment Clause. One of the premier examples of the tension between the religion clauses is accommodation of the religious exercise of military personnel, particularly in the limitations on personnel in uniform and the provision of military chaplains. The tension between the clauses has been illustrated in a number of military scenarios in recent years. For example, the U.S. Army recently allowed the first Sikh in more than 25 years to graduate from the officer basic training program without sacrificing the articles of his faith. The Army granted an exemption from the uniform policy, allowing the officer to maintain his unshorn hair and beard and to wear a turban as required by his faith. Some argue that allowing exemptions to the uniform policy diminishes esprit de corps and may weaken military effectiveness. Others assert that the exemptions allow for more individuals to serve in the military at a time when the forces have been stretched thin with the ongoing conflicts. They assert that it furthers an important public policy goal of ensuring that servicemembers of all faiths are an integral part of American military life and affirms the military's role as an assimilative national institution which has historically served to counter prejudice. In another example, the Don't Ask, Don't Tell Repeal Act was enacted in December 2010 and created a process to repeal the military's current policy regarding homosexual servicemembers once certain conditions are met. The repeal has raised several questions about the impact a new policy would have on chaplains whose religious background does not support homosexuality. Some argue that chaplains, as religious leaders, may be protected from providing support to homosexual servicemembers as a matter of conscience, similar to protections for doctors who have religious objections to abortions. Clergy and spiritual leaders traditionally benefit from heightened protection from claims of discrimination or unequal treatment of others, but it is also important to note that the military operates under a unique set of rules in contrast to the civilian society in which doctors and clergy may be afforded heightened conscience protections. This report provides an overview of the requirements of the First Amendment related to military personnel's religious exercise. It analyzes current constitutional and statutory requirements regarding religious exercise, and provides a framework for how Congress and the courts might consider future issues that arise related to servicemembers' religious exercise. Specifically, the report examines the limitations placed on servicemembers in uniform to exercise their religious beliefs. It also examines the role of military chaplains and the legal challenges associated with public funding for religious personnel. The report analyzes efforts by Congress and the Department of Defense to address the constitutional concerns that are raised by these issues. Religious exercise is protected by a number of different laws and regulations. Primarily, the protections and limitations on religion are based upon the Establishment Clause and Free Exercise Clause of the First Amendment. In addition to the First Amendment's religion clauses, the Religious Freedom Restoration Act (RFRA) supplements the standard of review of burdens on individuals' religious exercise to provide heightened protection not offered by the constitutional standard. Furthermore, the Department of Defense (DOD) has promulgated regulations addressing religious exercise in the military. The First Amendment of the U.S. Constitution provides that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof." These clauses are known respectively as the Establishment Clause and the Free Exercise Clause. Together, the clauses counterbalance the interests of individuals to practice their religious beliefs with a prohibition on government involvement in religion. At times, situations arise in which some government action would infringe upon an individual's religious exercise, but any corrective action that the government might take would raise concerns of establishment. Historically, the Free Exercise Clause protected individual exercise under a heightened standard of review for government actions that allegedly interfered with a person's free exercise of religion. The U.S. Supreme Court reinterpreted that standard in 1990. Since then, the Court has held that the Free Exercise Clause never "relieve[s] an individual of the obligation to comply with a valid and neutral law of general applicability." Under this interpretation, the constitutional baseline of protection was lowered, meaning that laws that do not specifically target religion or do not allow for individualized assessments are not subject to heightened review under the Constitution. In doing so, the Court indicated that individuals' right to freely exercise their religion exists only to the extent that they can do so while complying with laws that do not target religious exercise and apply generally to the population. In 1993, Congress enacted the Religious Freedom Restoration Act (RFRA), which statutorily reinstated the standard of protection of heightened scrutiny for federal government actions interfering with a person's free exercise of religion. RFRA provides that a statute or regulation of general applicability may lawfully burden a person's exercise of religion only if it (1) furthers a compelling governmental interest and (2) uses the least restrictive means to further that interest. This standard is sometimes referred to as strict scrutiny analysis. The Supreme Court has held that in order for the government to prohibit exemptions to generally applicable laws, the government must "demonstrate a compelling interest in uniform application of a particular program by offering evidence that granting the requested religious accommodations would seriously compromise its ability to administer the program." The constitutional understanding of the Establishment Clause is more complicated than the relatively straightforward rule for the Free Exercise Clause. The Court has used a variety of different tests to determine whether a particular government action violates the Establishment Clause. Historically, the primary test used to evaluate claims under the Establishment Clause is known as the tripartite test, often referred to as the Lemon test, derived from Lemon v. Kurtzman . Under this test, a law (1) must have a secular purpose, (2) must have a primary effect that neither advances nor inhibits religion, and (3) must not lead to excessive entanglement with religion. Although the Lemon test is the one commonly employed by the Court, it has been criticized by some Justices who have applied the test in different ways. One examination focuses on whether the government has endorsed religion. The government is prohibited "from making adherence to a religion relevant in any way to a person's standing in the political community." Another application of the Lemon test focuses on neutrality as the governing principle in Establishment Clause challenges. Under this interpretation, the essential element in evaluating challenges under the Lemon test is whether or not the government act is neutral between religions and between religion and non-religion. In addition to the Lemon test, the Court has used two other tests to evaluate Establishment Clause claims. One test considers whether coercion is threatening religious freedom and forbids the government from acting in a way that may coerce support or participation in religious practices. Another test permits government acts that involve religion if the Court finds that the religious element has played a part in the history of the nation, or as the Court has phrased it, has become "part of the fabric of our society." The applicability of these tests often varies, and multiple tests may be applied in the same case. In some cases, particularly those discussed later in this report, the religion clauses cannot be considered in isolation from each other. The Supreme Court has considered a long line of cases involving issues that arise where these two clauses intersect, often referred to as permissive accommodation of religion. The Court's approach to governmental accommodations of religion has developed over the past 60 years. Accommodation cases typically ask whether a government action that facilitates an individual's religious exercise in order to comport with the Free Exercise Clause can be considered an unconstitutional support of religion under the Establishment Clause. These situations often arise in the context of religious expression in schools, which is the subject of many of the cases that illustrate the requirements of accommodation. It is important to remember, however, that while the general principles of the analysis would remain the same, the military and schools both have unique characteristics that distinguish them from accommodations offered to society at large. The Supreme Court has indicated that the framework of analysis depends on the unique needs of the particular context in which the issue arises. In the military context, this means that the Supreme Court has recognized that military decisions are entitled to a higher level of deference so that the military may maintain order and discipline within its ranks. In 1948 and 1952, the Court decided two similar cases related to accommodations of religion with different outcomes, illustrating the distinction between permissible accommodations and unconstitutional accommodations. In McCollum v. Board of Education , the Court held that a program which allowed religious education teachers to teach in public schools on a weekly basis was unconstitutional. Four years later, in Zorach v. Clauson , the Court held that students could be released at their parents' request in order to receive religious instruction outside of the public schools. The Court distinguished between the cases because of the nature of the accommodation. In McCollum , the religious education occurred in public school classrooms during the public school day and students who opted not to receive religious instruction did not receive any alternative instruction during that time. In Zorach , the religious instruction occurred without the use of public school resources and allowed non-participating students to receive other secular instruction during the released-time program. It may be of interest to note that a concurring opinion to a later case related to religious exercise in public schools expounded on the constitutionality of the military chaplaincy. That concurrence noted that two factors were present in the accommodation of servicemembers' religious exercise that were not relevant in typical public prayer cases. First, membership in the military causes servicemembers to be isolated from their religious communities and opportunities for separate personal religious exercises for extended periods of time.