Section 51 is a subsecton of Section 51

Section 51 of the Australian Constitution

Section 51 of the Constitution of Australia grants legislative powers to the Australian Parliament only when subject to the constitution. When the six Australian colonies joined together in Federation in 1901, they became the original States and ceded some of their powers to the new Commonwealth...

 of the Australian Constitution

Constitution of Australia

The Constitution of Australia is the supreme law under which the Australian Commonwealth Government operates. It consists of several documents. The most important is the Constitution of the Commonwealth of Australia...

enables the Commonwealth Government

Government of Australia

The Commonwealth of Australia is a federal constitutional monarchy under a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement among six self-governing British colonies, which became the six states...

 of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 both to regulate and to participate in trade

Trade

Trade is the transfer of ownership of goods and services from one person or entity to another. Trade is sometimes loosely called commerce or financial transaction or barter. A network that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and...

 and commerce

Commerce

While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...

 with other countries and among the States

States and territories of Australia

The Commonwealth of Australia is a union of six states and various territories. The Australian mainland is made up of five states and three territories, with the sixth state of Tasmania being made up of islands. In addition there are six island territories, known as external territories, and a...

. The potential reach of s51(i) is very broad. The words "trade" and "commerce" in s51(i) also occur in Section 92 of the Constitution, where the expression used is "trade, commerce, and intercourse".

"Trade" and "commerce" have been broadly construed. The early case of W & A McArthur Ltd v Queensland held that the words extended to "the mutual communings, the negotiations, verbal and by correspondence, the bargain, the transport and the delivery".

In Australian National Airways Pty Ltd v Commonwealth

Australian National Airways Pty Ltd v Commonwealth

Australian National Airways Pty Ltd v Commonwealth 71 CLR 29 - most commonly known as Australian National Airways Pty Ltd v Commonwealth and also referred to as The Airlines Case or the ANA Case - was a High Court of Australia decision...

(ANA Case) (1945), the High Court held that the Commonwealth could use s51(i) to establish its own government-owned instrumentality in the form of the Trans Australia Airlines

Trans Australia Airlines

Trans Australia Airlines or TAA, was one of the two major Australian domestic airlines between its inception in 1946 and its sale to Qantas in May 1996. During that period TAA played a major part in the development of the Australian air transport industry...

, which had been established by the Australian National Airlines Commission, but could not prevent private sector competition.

Section 92 of the Constitution

Section 92 states that "trade, commerce, and intercourse among the States... shall be absolutely free". In the case of James v Commonwealth, the High Court decided that this requirement restricted the Commonwealth Parliament

Parliament of Australia

The Parliament of Australia, also known as the Commonwealth Parliament or Federal Parliament, is the legislative branch of the government of Australia. It is bicameral, largely modelled in the Westminster tradition, but with some influences from the United States Congress...

as well as State governments. This impacted on the Parliament's ability to exercise powers under subsection s51(i), regarding "trade and commerce with other countries, and among the States".