This chapter examines an important limitation on federal power: the limited guarantee of religious freedom provided by section 116 of the Australian Constitution. Section 116 prohibits federal laws, but not State laws, from: (1) establishing any religion; (2) imposing any religious observance; and (3) prohibiting the free exercise of any religion. Section 116 also prohibits religious tests for holding any office or public trust under the Commonwealth, whether that religious test is imposed by law or otherwise. There are very few cases considering section 116, with the consequence that the case law is not well developed. Section 116 was included in the Australian Constitution to ensure that the Federal Parliament would not be able to pass laws in respect of religion. There had been a concern from some religious minorities that federal laws might be enacted requiring people to participate in mainstream Christian observances.

Unlike modern originalists, Justice Joseph Story (1779–1845) endorsed the maxim that “Christianity is a part of the common law,” and he seems thus to have considered Christianity deeply entangled with the Constitution. A Harvard graduate and Massachusetts Unitarian, he did not consider the Constitution bound to any specific Christian orthodoxy. Rather, by the Revolution, American Christianity itself had become tolerant of differences in doctrine and worship, while sharing an understanding of moral duty, embodied in the common law. Thus he could at once subscribe to the proposition that Christianity is a part of the common law and decide religion cases so as to uphold the separation of church and state, protecting church property from state interference, and protecting a municipally-run school from clerical influence. On the issue of slavery, his commitments to a living faith and to a settled Constitution collided, calling into question the Christian constitutionalism to which he devoted his professional life.