It is often said that no government can legislate for commonsense. And it is also often said that the first thing every new Minister should do upon appointment is read and comprehend the provisions of the Cabinet Manual. Both statements are particularly apt in the case of Defence Minister Ron Mark.

The Cabinet Manual is the primary authority on the conduct of Cabinet government in New Zealand, and its confirmation and endorsement is always the first item of business considered by any new Cabinet upon taking office. It covers the full spectrum of Cabinet functions, including spelling out the roles and powers of Ministers, and their financial responsibilities and legal obligations. It also offers guidance as to how they should conduct themselves in carrying out their official duties and the management of any potential conflicts of interest.

In particular, the Cabinet Manual notes that, "... at all times, Ministers are expected to act lawfully and to behave in a way that upholds, and is seen to uphold, the highest ethical standards. This includes exercising a professional approach and good judgement in their interactions with the public and officials, and in all their communications, personal and professional." Elsewhere it notes that, "...In all areas of their work ... Ministers represent and implement government policy." Thus the scope for individual Ministerial action, particularly of the capricious kind, without the authority of the Cabinet, is constrained.

Now, there is an inevitable tension between the role as a Minister in the government, and the role as an individual Member of Parliament representing a political party. In these days of multiparty government, there will be times when the policy of an individual's party may not necessarily be the agreed policy of the government. These situations require a certain subtlety of judgement, something clearly lacking in the case of Mr Mark.

As a coalition partner, he is obliged to show clear support at all times for the collective government position, and in the words of the Cabinet Manual "... show careful judgement when referring to party policy that differs from government policy." Interestingly, a confidence and supply partner (like the Greens) are bound by a lesser standard being bound by collective responsibility only in relation to the particular portfolios they may hold, or when representing the government outside New Zealand.

Mr Mark's speech to veterans, apparently linking continued funding to political support for his party clearly did not breach the Cabinet Manual standard of acting lawfully. However, whether the essential crudity of his message that veterans and defence personnel should be voting New Zealand First "or else" met the "highest ethical standards" test and demonstrated "a professional approach and good judgement" is an entirely separate matter.

It may be easy and tempting to dismiss this incident as just another example of the immature strutting bluster and swagger that generally accompanies this Minister's behaviour, but that is no real defence. Any Minister, should, by virtue of the office they hold and their consequent seniority in the political process, know and act better, particularly after almost 20 years as a Member of Parliament, as in Mr Mark's case.

The more worrying aspect is that after almost eighteen months in the job he does not to have learnt the constraints that go with it. This is not to say that Ministers should be muzzled from making partisan political speeches - far from it, they are politicians after all, with a right to promote their re-election - but that they need to act with a dignity and decorum that was lacking on this occasion.

It all comes down to, as former Speaker Margaret Wilson once declaimed, a question of "hats" and people making it clear which hat they were wearing on a given occasion. Had Mr Mark been making his speech as a New Zealand First MP, and not as the responsible Minister, it probably would have no raised no eyebrows, which is where the good judgement question arises.

Yes, Ministers like the trappings of office and they way they are deferred to. They often make the mistake of assuming that gives their pronouncements a greater than normal authority, but there also times when Ministers need to become mere mortals again and make it clear when they are not speaking in a Ministerial role to meet the standards of the Cabinet Manual. The worry here is that even at this stage of his Ministerial career Mr Mark seems unwilling or unable to make and comprehend the distinction.

Mr Mark can feel relieved on one point though. The Cabinet Manual also makes it clear that, "Ultimately Ministers are responsible to the Prime Minister for their behaviour." As the Prime Minister has consistently shown in the case of the serially errant Mr Jones, that means no substantive action will be taken, so long as the Minister is from New Zealand First.