Constitutionality
The question of the constitutionality of the position of the Senate Chaplain (as well as that of the House Chaplain, and at times, that of military chaplains as well), has been a subject of study and debate over the centuries. Opponents have argued that it violates the separation of church-and-state and proponents have argued, among other factors, that the fact that the same early legislators who wrote the United States Constitution and its Bill of Rights, from which the position of "non-establishment" and church and state separation is derived, were the same ones who approved and appointed the chaplains.
President James Madison was an example of a leader who ultimately came to think that the positions of Senate and House Chaplains could not be constitutionally supported, although whether he always held this view (and to what extent he believed it at various times during his life) is a subject of debate. However it is clear from his "Detached Memoranda" writings during his retirement that he had come to believe the positions could not be justified:
Is the appointment of Chaplains to the two Houses of Congress consistent with the Constitution, and with the pure principle of religious freedom?
In strictness the answer on both points must be in the negative. The Constitution of the U. S. forbids everything like an establishment of a national religion. The law appointing Chaplains estabfishes a religious worship for the national representatives, to be performed by Ministers of religion, elected by a majority of them; and these are to be paid out of the national taxes. Does not this involve the principle of a national establishment, applicable to a provision for a religious worship for the Constituent as well as of the representative Body, approved by the majority, and conducted by Ministers of religion paid by the entire nation.
The establishment of the chaplainship to Congs is a palpable violation of equal rights, as well as of Constitutional principles: The tenets of the chaplains elected shut the door of worship agst the members whose creeds & consciences forbid a participation in that of the majority. To say nothing of other sects, this is the case with that of Roman Catholics & Quakers who have always had members in one or both of the Legislative branches. Could a Catholic clergyman ever hope to be appointed a Chaplain? To say that his religious principles are obnoxious or that his sect is small, is to lift the evil at once and exhibit in its naked deformity the doctrine that religious truth is to be tested by numbers, or that the major sects have a right to govern the minor.
The constitutionality question has been examined in a number of court cases. According to "House and Senate Chaplains: An Overview," an official 2011 Crs report created by the Congressional Research Service for "Members and Committees of Congress":
The constitutionality of legislative chaplains was upheld in 1983 by the Supreme Court (Marsh v. Chambers, 463 U.S. 783, related to chaplains in the Nebraska Legislature) on the grounds of precedent and tradition. The Court cited the practice going back to the Continental Congress in 1774 and noted that the custom “is deeply embedded in the history and tradition of this country” from colonial times and the founding of the republic. Further, the Court held that the use of prayer “has become part of the fabric of our society,” coexisting with “the principles of disestablishment and religious freedom.” This decision was cited in Murray v. Buchanan, which challenged the House chaplaincy, the next year. On appeal, the U.S. Court of Appeals for the District of Columbia dismissed the complaint “for want of a substantial constitutional question.” Subsequently, on March 25, 2004, the U.S. District Court for the District of Columbia, citing Marsh v. Chambers, dismissed a suit that challenged the congressional practice of paid chaplains as well as the practice of opening legislative sessions with prayer.
In 2000, a C-SPAN "public affairs on the web" response to the question of constitutional challenges noted that:
"In 1983, the Supreme Court upheld the practice of having an official chaplain as deeply ingrained in the history and tradition of this country. They stated the ultimate authority for the position lies in the Constitution which states that the House and Senate may each choose their officers, with no restrictions on what kind of officers may be chosen. Using that authority, both chambers have chosen to continue to elect an officer to act as Chaplain."
Read more about this topic: Chaplain Of The United States Senate