Latham was a conservative man. He served as an intelligence officer in the Royal Australian Navy during the First World War, later became head of Naval Intelligence in 1917, and was part of the Australian delegation to the Paris Peace Conference in 1919. His military service gave him a lifelong distrust of communism.

Later, he served as a politician in Federal Parliament, first as an independent, then for the Nationalist Party, and finally for the United Australia Party, the predecessor of today’s Liberal Party. Latham was Attorney-General during the British seamen’s strike of 1925, which spread around the world. Latham was a strong opponent of union militancy, and drove through changes to the Commonwealth Crimes Act to facilitate the deportation of two of the ringleaders of the strike in Australia. Later, he amended the Crimes Act again to make sending communist propaganda through the post an offence.

In 1935, he was appointed Chief Justice of the High Court by Prime Minister Joseph Lyons, and was succeeded as Member for Kooyong, and Attorney-General, by the young Robert Menzies, a future Prime Minister of Australia.

Dixon is widely regarded as one of Australia’s greatest judges; indeed, one of the greatest judges of the common law world.

Dixon was a scholar of Greek and Latin classics, but still apparently an entertaining conversationalist, and during his time as a barrister in Melbourne, became close friends with Sir John Latham and Sir Robert Menzies. He was appointed to the High Court in 1929 by Prime Minister Stanley Bruce, on the advice of Latham, then Commonwealth Attorney-General, later to become Chief Justice. In later years, Dixon said he had never enjoyed being a judge, and much preferred being a barrister. Nevertheless, Dixon’s brilliance at legal reasoning, and skill at working with his sometimes difficult fellow judges, saw his appointment by Menzies as Chief Justice in 1952. Dixon also served as Australia’s ambassador to the United States for a few years during the Second World War, and was later appointed as a UN mediator between India and Pakistan over the status of Kashmir, where he wrote a report that some commentators continue to acknowledge as the best foundation for an agreement over that disputed territory.

However, Dixon, a staunch Anglophile, was also a supporter of the White Australia Policy, which he saw as protecting British interests in Australia. Similarly, his support for British interests manifested itself in strong anti-Catholicism.

McTiernan is the longest-serving justice in the history of the High Court. A firm Catholic, he was known as a polite and quiet man, who never responded to the criticisms made of him and his appointment to the High Court.

McTiernan had served in the New South Wales Parliament under firebrand Labor Premier Jack Lang, and was serving in Federal Parliament in the Australian Labor Party, when he was appointed by Prime Minister James Scullin in 1930, at the age of only 38. His appointment was criticised on the grounds that it was too “political,” and that McTiernan lacked sufficient legal experience. Nevertheless, he went on to serve as a High Court justice for another forty-six years.

He retired in 1976, after the Chief Justice of the time, Sir Garfield Barwick, a former Liberal politician, refused to include a wheelchair ramp in the design of the new High Court building, preventing McTiernan, who had broken his hip in a fall earlier that year, from accessing the building easily.

Williams, like Latham, saw military service in the First World War, serving in the British Royal Field Artillery on the Western Front. He won the Military Cross, and was promoted to captain. After the war, he returned to Australia, and became a barrister, specialising in equity, intellectual property, and tax cases. He was another quiet and conservative man, who could not match the intellectual brilliance of colleagues like Owen Dixon or Wilfred Fullagar, but won a reputation as a hardworking, polite, and warm man, with a particular taste for sport and musicals.

He was appointed to the New South Wales Supreme Court in 1939, and elevated to the High Court by Prime Minister Robert Menzies in 1940. Towards the end of his career, he is said to have regretted this elevation, wishing he had stayed in New South Wales and focused on those equity cases which were his true professional love.

A grave and serious man, Webb is famous around the world for his time as president of the International Military Tribunal for the Far East, which tried Japanese military and political leaders for war crimes committed during the Second World War. During the Second World War, he was also commissioned to investigate and report on Japanese crimes in Papua New Guinea, and against Australian prisoners of war.

Although sometimes accused of Labor sympathies, and appointed to the High Court by Labor Prime Minister Ben Chifley in 1946, Webb remained so staunchly independent and non-partisan during his time on the bench that later commentators have described him as “colourless,” although admitting that he was extremely conscientious.

Fullagar was regarded as a brilliant judge around the world, and his death in 1961 brought rare tributes from the House of Lords in the United Kingdom, and the United States Supreme Court, as well as from his friend Sir Owen Dixon, who described him as having a “most lovable nature,” in addition to the depth and breadth of his learning, and his erudite writing style.

Dixon and Fullagar had been friends since their early days as barristers in Melbourne, where Dixon and Sir John Latham lent Fullagar the money he needed to go into business, and Fullagar and Dixon bonded over their shared love of Greek and Latin classics. After less than a year as a barrister, Fullagar was elevated to King’s Counsel, a prestigious appointment equivalent to becoming a senior barrister. He was appointed a judge of the Victorian Supreme Court in 1945, and elevated to the High Court by Prime Minister Robert Menzies in 1950.

Like Latham and Williams, Fullagar saw military service during the First World War, serving in the Australian Field Artillery.

Kitto was another of Sir Robert Menzies’ conservative appointments to the High Court, being so elevated in 1950, and retiring only in 1970. An equity lawyer by trade, Kitto is remembered today often for his dense and complicated writing style. He was an opponent of judicial activism, or the introduction of policy concerns into judicial decision-making, calling it the introduction of “deleterious foreign matter in the water of the common law – in which, after all, we have no more than riparian rights.”

After retiring from the High Court, Kitto was the inaugural chairman of the Australian Press Council, arguing against the introduction of uniform national defamation and privacy laws, which he regarded as intrusions on the freedom of the press.

Latham was the only judge to find the Act to be valid. In particular, his dissent relied on two considerations to argue that Parliament, and not the courts, should have the final say in determining the validity of defence legislation.

First, Latham underlined the fundamental importance of defence policy, pointing out, quoting Oliver Cromwell, that “being comes before well-being.” In other words, the defence of the Commonwealth is a fundamentally important power, which, if not exercised properly, will preclude the exercise of any other powers of the Commonwealth, because there will be no Commonwealth.

Next, Latham argued that as well as being fundamentally important, defence policy is inherently political. It is not able to be determined only by appeal to facts that might be proven by evidence admissible in a court; it is often made based on a variety of factors, and involves many matters of ‘judgment.’

Comparing the possible danger of the Communist Party in Australia to the declarations of war in the First and Second World Wars, Latham pointed out that those declarations of war were viewed by some as necessary for the defence of the Australia, and by others as simply imperialist adventures; they involved a degree of judgment on the part of Parliament. However, neither declaration was made by the Court, or reviewed by the Court, and nor should they have been.

These two considerations, said Latham, made the defence power different from the other allocated to Federal Parliament by the Constitution. The Court ought to give Parliament more leeway in its exercise of the defence power. It was not up to courts, Latham argued, to second-guess Parliament in determining who the enemies of the Commonwealth were, and what level of danger they posed. They should only inquire into whether the means adopted by Parliament were consistent with the dangers that were supposed to exist.

In other words, the Court should have inquired whether the content of the Act was sufficiently connected with Parliament’s intention to alleviate the dangers posed by communists in Australia, but not whether Parliament was allowed to designate communists in Australia as posing that level of danger. Since the Act clearly adopted measures that would alleviate the danger said to be posed by communists in Australia, Latham argued, it was valid.

Dixon’s judgment was in stark contrast to Latham’s. In Dixon’s view of the Australian federal government, the judicial branch is the one tasked with deciding whether particular legislation is a valid exercise of the limited powers of Parliament, and the importance of preserving and defending the country does not exclude laws like the Communist Party Dissolution Act from this set-up.

First, Dixon rejected the executive power of s 61 as a source of validity for the Act. As he said, this power is directed to maintaining government in the constitutionally-prescribed form; it is not a power to maintain the federal government at all costs. That power may also exist in extreme situations, but it is not to be found in the Constitution. All constitutional powers are governed by constitutional limitations and assumptions, and, for Dixon, one of the most important constitutional assumptions in this context is the rule of law. The vague phrases and lack of objective criteria of the Act, combined with the broad powers granted to the executive branch, violated some of the core tenets of the rule of law.

Next, Dixon turned to the defence power. He agreed that certain actions of the federal government which would be invalid in a time of peace, may be valid in times of war, because of the expanding nature of the defence power. He also acknowledged that Australian troops were fighting in the Korean War at the time the Act became law, and he acknowledged the various other international incidents which pointed to the growing enmity between communist and non-communist countries.

However, at the end of the day, Dixon said that the situation in Australia was not dangerous enough to justify such a law as a legitimate use of the defence power in s 51 (vi).

Like Dixon, McTiernan’s starting-point was that the Act’s preamble was “in no way decisive of the question whether the Act is valid or invalid, for that is a judicial question which only the judicature has the power to decide finally and conclusively.” Thus, he firmly reiterated the view that it is the High Court, and not Parliament, who will have the final say on the Act.

Next, McTiernan distinguished between the powers of Parliament in a period of emergency, and a period of peace. In a period of emergency, Parliament’s powers expand, or rather the scope of the defence power enlarges, and Parliament may perhaps be allowed to designate certain individuals or organisations as security threats, and control their civil liberties. However, in a period of peace, the defence power is not large enough to encompass such legislation.

The question, McTiernan said, of whether a period is one of emergency or peace, and what measures should be taken, are questions for Parliament. However, the High Court retains its ability to decide whether the measures Parliament proposes have a reasonable relation to the emergency.

However, despite asserting that whether this was a period of peace or emergency is one for Parliament, McTiernan then went on to argue, like Dixon, that, at time the Act was passed, there was no emergency sufficient to give Parliament control over the civil liberties of communists; the defence power was not sufficiently enlarged. Thus, the Act was invalid.

Williams’ starting-point was different from McTiernan’s. Williams argued that, because the defence power waxes and wanes depending on the “dangers to the security of Australia that exist from time to time,” it is all the more important for a Court which is trying to determine the validity of legislation under the defence power to be informed about those dangers.

In other words, the question of whether a period is one of peace or emergency is something the Court should be thinking about too, not just Parliament. It is a central question to determining the extent of the defence power, and thus the validity of a lot of legislation.

Thus, Williams asked, what were the dangers to Australia’s security? Despite the fact that Australian troops were fighting in the Korean War at the time, Williams (as well as most of the other judges) said Australia’s security was not really threatened very much at all. The time was not one of “grave crisis,” during which “hostilities [are] waged on large scale,” like the Second World War had been. Thus, the defence power did not extend to this kind of legislation.

Williams also discussed the fact that the legislation, in the words of former High Court Chief Justice Sir Adrian Knox, “prohibits no act, enjoins no duty, creates no offence, imposes no sanction for disobedience to any command, prescribes no standard or rule of conduct,” but instead imposed penalties on certain individuals and organisation just because they existed, and were deemed to be a threat.

In other words, there were no objective criteria by which the behaviour of the individuals or organisation could be measured and criticised. Since the Court’s role, for Williams, was to examine exactly such objective criteria, and to decide whether they were reasonable, given the level of danger to Australia’s security, the Act was also problematic. An example of an Act that might have been more to Williams’ liking was the sedition provisions of the Crimes Act. There, certain types of behaviour were prohibited, rather than certain individuals and organisations being penalised.

Webb’s reasoning was somewhat different from the other judges.

Reviewing previous case law, Webb came to the conclusion that, if the threat posed to Australia’s security by communists was only a short-term threat, then the Act would be invalid. This was because the severity of the consequences attaching to those people declared to be communists under the Act would be unreasonable and disproportionate to the danger they posed, and thus not supported by the defence power.

However, if the threat posed to Australia’s security by communists was a more long-term threat, the Act would be valid; the severe consequences would be reasonable and proportionate to the danger.

Thus, Webb said, it was the responsibility of the Commonwealth, who was arguing that the Act was valid, to prove that the ‘facts’ asserted in the preamble were true, and that the threat posed to Australia’s security by communists was a long-term threat. Since they didn’t attempt to do that, Webb found the Act was invalid.

Fullagar established two powers in the Constitution upon which the validity of the Act could rest. The first was the defence power, and the second was an inherent power of the Commonwealth to protect itself against subversion.

Fullagar’s judgment is most famous for his explanation of the two aspects of the defence power. He argued that the defence power supports two different sorts of laws. The primary aspect supports “laws which have, as their direct and immediate object, the naval and military defence of the Commonwealth.” This would include laws about enlistment, military training, ship building, and so on. These form the core of the zone of power granted to the Parliament by the defence power. This core will exist in times of war, and in times of peace.

The secondary aspect is more supplementary, and supports laws which are a bit further removed from the classical idea of naval and military defence, but yet still relevant. These include laws about food rationing, price controls, employment conditions in key industries, and so on.

However, Fullagar argued that it is typically only in situations like the “commencement or immediate apprehension of war,” or the “period necessary for post-war readjustment,” where this secondary aspect of the defence power has been recognised. In other words, some kind of grave crisis is necessary before the secondary aspect of the defence power arises. Without these conditions, only the primary aspect of the power exists. Deciding whether the necessary crisis exists, and the secondary aspect of the power has been enlivened, is a job for the Court.

In this case, Fullagar decided that the state of affairs that existed at the time the Act was passed was not grave enough to make the Act valid as an exercise of the secondary aspect of the defence power.

Fullagar also decided that the inherent power of the Commonwealth to protect itself against subversion could not support the Act. This was because this inherent power was also open to judicial investigation, and the Act did not provide an objective link between the individuals and organisation to be penalised, and the necessity of penalising them in order to protect the Commonwealth against subversion. Without such an objective link, Fullagar held, the Act could not be valid as an expression of this inherent power either.

Kitto’s starting-point was also that Parliament’s opinion of the extent of its powers is not conclusive, and that the High Court must have the final say in determining the constitutional validity of all legislation.

In other words, while the “the necessity or desirability of [the Act], if it be within power, is a matter with which the courts have no concern,…the question whether the legal operation of the measure has such a capability of aiding defence as gives it that character which alone will sustain it as an exercise of the defence power is a matter which no judgment of the Parliament can conclusively decide.”

Kitto asserted that he doesn’t think the Act has such a character that links it to the defence power in s 51 (vi) of the Constitution, or any other enumerated power of Federal Parliament. Accordingly, the Act was invalid.