Constitutional Conventions In Westminster System Of Government
Many rules are followed by political institutions in countries using the Westminster system of government that are neither codified in legislation nor formalised by judicial decisions. These unwritten laws have been referred to in the past as rules of political morality and the unwritten maxims of the Constitution, but have since eventually been solidified into the generally acknowledged term of a constitutional convention primarily due to the influence of British legal scholar Albert Dicey. 
There are different views as to what form a constitutional convention takes, one being that of a descriptive statement based on what actually happens and two, that it is a prescriptive statement on what should happen based on ethical and constitutional principles.  Neither is incorrect. As with the first view, some conventions exist and are followed merely because they are the widely accepted routine practice and in regard to the second view some are formed based on, ethical principles that would give rise to a sense of constitutionalism if followed and the reverse if not.
How and why they exist
It was the intention of the founders of the Constitution, that they would only set the essential elements of responsible and representable government, leaving a non-solid outline of evolving practices and usages.  The constitution and system of government, including the conventions within, are a much wider concept than the written law of the constitution and have allowed the government to evolve and adapt to expectations, morality and society.  Conventions are even more pertinent in the United Kingdom which does not have a formal written constitution.  Constitutional conventions are significantly important in Australia as well, as it is through them that the system of cabinet government has developed. 
Some well established and widely known conventions may have developed to avoid the formality of a change of law, the development of these practices allows for legislation on that particular aspect to be avoided, essentially saving the time, money and publicity that would otherwise go into making or changing legislation. 
The development of conventions is one of growth rather than planning. For example, whilst originally and still at law, the Constitution provides that the Governor-General is appointed by the Queen, the current practice is that the Governor-General is chosen by the current Prime Minister. Should the Queen attempt to choose the Governor-General in Australia today this would most likely be met with the disdain of being contradictory to good constitutional practice. However, if the same was attempted closer to the time this convention was first adopted, it would most likely not have been considered so. 
It is not uncommon for a convention and law to intersect. The convention of the Prime Minister selecting the Governor- General covers the same subject matter as the law which allows the Queen to be able to select the Governor-General. As is the case in the prior example, one may be thought to be more important and nullify the other.  This is because the prior would be considered unconstitutionally outdated. Other minor conventions have developed over time from social rules and the accepted business dealings of the government. 
Disputes may arise in regard to conventions as to their existence, content and their enforcibility. It is also true that conventions are not laws and that minor ones may, and most probably are, broken or ignored much of the time without penalty. However, the more important conventions are enforced in a variety of ways.
Enforcement via Responsibility
Often the outcome of disputes depends on public opinion, the doctrine of responsible government makes this possible, which underpins the entire constitution at its core.  Conventions regulate the conduct of those holding public office and such persons wishing to hold such roles much observe the restraints which are imposed upon them.  Whilst this doctrine was never formalised into the legislature of the Constitution, it is considered to be part of the fabric on which the Constitution is superimposed.  When a government member acts in a way that is considered out of line with the preconceived notions of their office or stature, even if it doesn't breach law, usually peers, opposition or public opinion demand them to relieve themselves of their position. Positions carrying roles which have now become more limited via convention, such as that of the Governor- General in relation to the executive powers now conventionally run by the Prime Minister and cabinet, know that to overstep these conventions, even though the law states differently, would no doubt bring about the abolition of the tentative power they still hang onto. 
Conventions are not only followed because of the negative implications that would befall those who did not. They also express a constitutional value that should be strived for within a responsible government. 
Enforcement via Law of the land.
Dicey argues that public opinion is only one way ensuring that these conventions are enforced. Some conventions are actually secured by the law of the land. Giving an example from the United Kingdom at the time, namely the convention of parliament assembling once a year. If parliament had breached this convention a variety of things would be set in motion. The Annual Army Act would expire resulting in any attempt to control the army being a breach of the law, if it acted on its own this would be detrimental to any member of the army, whose actions would find them liable in at law. Large portions of tax could not be collected without the collectors finding themselves in breach of the law. Subsequently, what tax was collected would be done so illegally, and therefore, not legally be able to be spent. All this would find the government not only opposed but helpless and in disarray. This convention, whilst not legally enforceable, nevertheless could not be neglected without the consequence of thousands of people committing illegal acts that would be recognisable in a court of law. 
Enforcement via courts
Canada has even gone as far as having used the Supreme Court as a source for authority on conventions where disputes have arisen.  In Australia, conventions have been found to have a role in interpretation of acknowledged constitutional laws as well as in cases.  Specific conventions such as that regarding the existence of the executive government have been recognised by the High Court in Australia. 
2. How important is the role conventions play?
Range of conventions
Constitutional conventions, as previously discussed, cover a broad and varying range of areas. Whilst some are relatively minor and are basically ignored or not adhered to on a daily basis, others are important and in certain circumstances, circumvent the actual written word of the Constitution. 
Important Australian Conventions
Many important conventions govern aspects of the constitution, such as that of the officer of Prime Minister, a role not even mentioned in the written Constitution.  Instead in the Constitution all executive power is given to the Governor-General. During the 1983-1985 Constitutional Conventions, the more important aspects of these were laid out.  One in particular ensures that the Queen and Governor-General only receive advice from Australian ministers and not United Kingdom ministers when acting within their power. Whilst many conventions, actually still invoke the Governor-General and Queen in seemingly powerful situations, they all appear to be only or on the advice of the Prime Minister.
Conventions were further recognised in the areas of appointment of the Governor-General, who in the written Constitution was actually appointed by the Queen. However, now that appointment is on the advice of the Prime-Minister. There is also an inability of the Queen to interfere with the Governor-General and the powers gained by the Governor- General are not exercisable by her. It should be noted that these conventions clearly provide for a shift of power from Britain to Australia, preventing the United Kingdom from acting under the formal Constitution, as such actions would be found to be unconstitutional in modern Australia.
There are also conventions outlining the composition and operation of executive government. Considering that the written constitution does not outline the vast majority of these, it is essentially important to the very running of the country that these conventions exist and are adhered to.
When conventions fail.
In 1975 there was what is referred to as a constitutional crisis which involved a convention implying that if a position in the Senate was vacated, someone from the same party would fill it. In a successful attempt to oust the labour government, the opposition was able to block supply in the Senate with the support of non-labour senators who had been chosen by non- labour states to replace labour senators. Although this was technically legal, there was a convention that the Senate should not do so unless under extraordinary circumstances, which was tactically ignored.  This led to a stale-mate which forced the Governor-General to intervene. Codification would solve a crisis like this from happening again.
3. Should some conventions be codified?
One view is that constitutional law should consist of these conventions which are recognised as obligatory by the three branches of government.  Another is that the Constitution should be changed to incorporate these conventions in order that an average citizen would be able to understand it on its own.  Others believe that merely establishing these conventions as something with less standing than the law but with more importance than mere practices, would suffice. Another opinion is that there would be nothing to be gained from codification. Many agree that codification would be an onerous task, not to be taken lightly. 
After the 1975 crisis, steps were made to attempt to give conventions more recognition and substance. At the guidance of Professor K.W. Ryan, who provided an opinion accepted by the 1978 Constitutional Convention, that it would be undesirable to have these rules enforceable at court and unnecessary if they did not, instead suggesting a non-legal statement of conventions with authority based on those who created it and its general acceptability.  These were then debated in 1983 and a set of 34 conventions were agreed upon which mainly concerned the executive government, power of the Queen and that of the Governor-General. Due to the issues of the 1975 crisis, in another Convention in 1985, a further 18 conventions concerning the Governor-General’s powers were also formulated.  Later, issues were raised as to what authority these conventions had. There were complaints about the inevitable minor or major changes that came from interpretation, discussion and refinement. There were also questions over the factual information on how large or small a majority a convention attracted when agreed upon and concern was expressed over the potential weakening of conventions which were not mentioned. 
Reasons against codification
A codified form of conventions would be hard pressed to keep up with the inevitable evolution of socially considered constitutional values, as well as the actual practices of the government. It would also be impossible to prevent the process by which non-legal rules modify formal rules from starting all over again.  If alternatively, conventions were not recognised as conventions until acceptance and codification, then the evolution of the system and ability for the government to keep up with its current business practices would no doubt be heavily affected in this regard. The form of conventions allows for them to exist only as long as necessary, without having a long term effect as a legal rule would.  Both of these approaches would impair the evolution of law and government, making it much more difficult for politicians and those involved in the constitutional process to keep the law in line with what the modern populace would consider to be constitutional.
It is possible that conventions could be enacted by legislation. However, due to the nature of conventions, being of such a broad and evolving character, much time would need to be delegated to working out the specifics of each individual convention, evaluating conflicts that would inevitably arise and developing necessary future conventions. Due to the diverse subject matter of a convention it would not realistically make sense for them to be put in the same piece of legislation together.  To further complicate matters, whilst some conventions are firm and have clarity, others are relatively vague and no one really comprehends where the boundary lies.  Even some well established conventions may be vague in application, with interpretation open to argument. Such arguments when they arise are hardly ever definitively resolved.  Frequently, arguments about the existence of conventions are so complex and arguable in nature that they span years. Such was the case in 1973 where letters from the Queen, refusing a State’s petition to the Privy Council, generated a heated debate lasting into the 1980's. This involved preconceived conventions which provided in what circumstances the Queen is advised by which country or State’s ministers and the United Kingdom's neutrality to the conflict between States and the Commonwealth. Whilst all these conventions were later deemed unnecessary by the Australia Act,  government information now available from the United Kingdom shows nearly all these conventions to be false. The relevant point being that it still took years for the specifics of the conventions to be agreed upon and generated much debate. 
Reasons for codification
Codification would create a more legally bound government and political structure, where what were once guidelines would be enforceable at law. This would no doubt be in the public interest of having a more transparent government. Having a constitution of accurate description would allow for the public to more easily judge actions committed by politicians as either constitutional or unconstitutional. Political entities would also know their boundaries and could subsequently further refine and define their roles and actions based on such. The issues involving conventions being unwritten in any authoritative sense has lead to problems over their content, existence and the willingness to adhere to them, as was the case in the 1975 constitutional crisis as previously discussed. 
Whilst currently many constitutional conventions maintain a level of secrecy, one view is that the more information available to the public on such matters, the more easily those in charge of making decisions or commenting on constitutional decisions would be able to come to an agreement on the appropriate action. The secrecy of these conventions can lead to misinterpretation of the current form of the constitution, as was seen in the events of the 1973 State's appeal to the Privy Council. At the very least increased public access to government documents on constitutional conventions would give more substance to the conventions without codification. 
There are views that the current form of the constitution is a mystique of ineffability, something only professionals and those knowledgeable can comprehend. It has been argued that it would be preferable if the constitution was modelled as such to refer to simple statements about what the actual political system is. As previously discussed, the current Constitution still infers that inherent executive and military powers are given to the Queen and the Governor- General and makes no mention of the conventions prevalent to the Prime Minister’s office, cabinet or indeed the need for a government to maintain a majority of seats in the Lower House. What there is of the current practice of government in the Constitution is obscure and dominated by many obsolete provisions, that those not knowledgeable in the area would easily fail to understand its meaning.  This argument is certainly feasible. Why shouldn't the written Constitution, the formal document at the country’s core, at the very least cover the accurate basics of the nuts and bolts of the country’s political system? Whilst actually amending the written constitution may be too large a step for those who have already theoretically completed this process via conventions, a step in the right direction would no doubt be codification of the primary conventions regarding the Prime Minister, cabinet and the workings of parliament. This would refine the number of sources, that a citizen not versed in legal or political issues, would have to search through to find the workings of their own government.
Whilst attempts have been made to provide certain conventions with more recognition, politicians seem reluctant to give them further, legal authority. Part of their reluctance no doubt would be the increased accountability, which whilst for them is a downside, is an upside for the citizens. Nevertheless, as previously stated, to adopt these conventions as legal rules would inherently hinder the evolution of constitutional law and government, by giving less power to any future non-legal conventions that would be certain to arise and more power to a convention that could soon be outdated. The issues of the time required and the conflicts over defining conventions makes codification of every single convention an impossibility. However, it would benefit Australia to at least adopt legislation in a genuine attempt to bring together the more important conventions, such as those relating to the Prime Minister, cabinet and government. This would allow for a more fundamental acknowledgment of the rules leading to a better understanding by both the public and government of our political system and to the adherence of these rules. But even if such a legislation were to take place, what would be there to stop the further implication of future conventions from overwriting them? This of course, as mentioned prior is a requirement for the constitution to evolve and remain what is deemed constitutional by modern standards. Accordingly, future conventions would have to be allowed to be recognized over the codifided ones, so that the codified ones could be changed or modified to bring them in line with society's current standards and norms. If such was allowed this would be a fruitless endeavour in the first place, as conventions would continue to fufill the same nessecary role they have now.