A constitution is a body of rules which regulates the system of Government within a state. It is a document which incorporates the principle rules governing the structure and functions of the Government. It regulates the relationship between the state and its citizens.
The United Kingdom does have a constitution but because it is not written, it can be argued that one does not exist. The fact that the UK’s constitution is unwritten, allows it to be flexible/ amendable. Parliament can simply repeal laws by a simple majority. Changes can be made without having to amend existing legal rules. It is therefore easy to change to change the law, making it easily adaptable to a constantly changing society and times. One source of the constitution are constitutional conventions.
Constitutional conventions can be defined as sources of the United Kingdom’s constitution that are not legally binding but are however, politically enforceable. They ensure that the legal powers of our constitution are implemented in accordance with democratic principles. They are a set of rules of behaviour that must be followed in order for the constitution to work. Constitutional conventions can be seen as a means of bringing about change without formal change to legislation thus giving the constitution flexibility which is crucial in a changing society.
The conventions cannot be enforced by a court of law as they conflict with legal rules which they propose and courts are bound to enforce those legal rules. The Supreme Court of Canada stated that the conflict that exists between convention and law means that there no convention, no matter how well-established or widely accepted it is, it cannot be made into law unless a law was enacted to codify that convention. This principle became authoritative in the UK.
A.V. Dicey, an influential constitutional theorist of the 19th century, referred to these rules as “conventions, understandings, habits or practices, which though they may regulate the conduct of several members of foreign power….are not in reality laws at all since they are not enforced by the courts”.  Dicey stated that although these rules are not strictly laws, disobeying them would ultimately breech the law itself.
Much discussion of constitutional conventions has suggested that conventions give rise to binding rules of conduct.
John Mackintosh described the conventions as ‘a generally accepted political practice, usually with a record of successful applications or precedents’.  Other authors describe conventions as “rules of constitutional behaviour which are considered to be binding by and upon those who operate the constitution but which are not enforced by law courts…nor by the presiding officers in the Houses of Parliament”. 
Sir Ivor Jennings viewed conventions as the ‘flesh which clothes the dry bones’ of the law  .
Peter Hogg, a Canadian scholar stated:
‘Conventions are rules of the constitution which are not enforced by the law courts. Because they are not enforced by the law courts they are best regarded as non-legal rules, but because they do in fact regulate the working of the constitution they are an important concern of the constitutional lawyer. What conventions do is to prescribe the way in which legal powers shall be exercised. Some conventions have the effect of transferring effective power from the legal holder to another official or institution. Other conventions limit an apparently broad power, or even prescribe that a legal power shall not be exercised at all’. 
There are various examples of constitutional conventions, one of which is that the Crown must accept and act on the advice of the Government/ his or her ministers. The Crown cannot ignore the advice they are given unless they are to exercise reserve powers. Dicey wrote that conventions were designed to control the monarch’s use of their discretionary power. It can be argued that this convention should not be codified in order to allow the Queen a reserve power should she need it. For example in an extreme circumstance such as a nuclear launch decision, she may want to veto the decision made. Although it is unlikely for such an extreme circumstance, someone who is impartial to politics is needed to make the decisions.
Another convention would be the Crown granting Royal Assent to all legislation. As Parliament is elected and all legislation is debated in the House of Commons, it can be argued that they represent public opinion more than the Queen does. It can therefore be suggested that this be codified in order for it to remain as a symbolic gesture to the monarch.
In 1708 the Royal Ascent was withheld from a Bill that the monarch in question, Queen Anne disapproved of. It can be argued that this is unconstitutional and undemocratic. However it may also be argued that if this convention remains uncodified it offers limits on parliamentary sovereignty and powers under the circumstances of a Bill being processed and attempted to be passed at a fast rate without being scrutinised fully. Dangerous Dogs Act 
Another convention would be that if the Government loses support in the House of Commons the Prime Minister should advise the Queen to dissolve Parliament. It is argued that this convention should be strictly codified, as the issue of legitimacy undermines the whole democratic process. The precedent should be set as to what percentage of the house the Party in power should control to stop any calls of illegitimacy of a weak Government. For example: If the Conservatives ruled without the Liberal Democrats, the percentage of a no confidence vote would clearly have to be set out.
Australia’s political system is founded on the principle of ‘responsible Government’. Its basic beliefs are that, Parliament is supreme; the Government is responsible to Parliament; all ministers have to be in Parliament; regular elections must be held; and there is a professional bureaucracy that is independent but accountable to ministers.
Unlike the United Kingdom, Australia has a written constitution and some of these principles are captured in that document. The provisions of the constitution comprise the formal rules of Government. But formal rules are only part of the story about how a system of Government operates. In areas about which the constitution is silent, political behaviour is guided by ‘well established practice, methods, habits, maxims and usages’ many of them long-standing which were inherited from colonial parliaments, which in turn inherited them from Westminster. It is these practices, methods and usages, which tend to be referred to as ‘conventions of the constitution’
Governor-General and Governors always act on the advice of their Prime Minister or Premier or other relevant minister.
In turn, Prime Ministers and Premiers ensure they have support, advise an election or resign.
After an incumbant prime minister loses an election, it is expected that they will advise the governor-general to appoint the leader of the larger party as prime minister so the governor-general does not need to act on their own initiative.
State premiers tender advice for Senate elections in response to the Prime Minister’s decision.
State governors are given a dormant commission to administer the Commonwealth if the Governor-General is unable to.
Vice-Regal officers act in a politically neutral way, and do not vote.
No convention is absolute; all but one (the third) of the above conventions were disregarded in the lead up to or during the constitutional crisis of 1975.
Ignoring constitutional conventions does not always result in a crisis. After the Tasmanian state election, 2010, the Governor of Tasmania rejected the advice of his Premier to appoint the leader of the opposition as premier because he felt the advice was tendered in bad faith. The Premier went on to form a new government.
It can be argued that conventions should not be codified as they offer a flexibility in terms of they can be changed if need be where as a codified convention can not.
If a convention is codified it then becomes legally enforceable and one could be punished for violating them no matter how minor.
As some legally binding rules are not codified, if you were to codify these conventions and give them legitimacy they could override existing law as they would be given a special status above uncodified legally binding rules.
Each codified convention would be clarified and not open / would avoid misinterpretation
Currently there is a lack of certainty as to the scope and even the existence of certain conventions.
Certain interpretations of conventions may evolve over time. As they are currently not codified this affords government flexibility in terms of changing / implementing these conventions.