It is not just that an organisation whose membership ranges from sole practitioners in the provinces to members of Britain's biggest firms has trouble convincing the sceptics that its approach is consistent, there is also the problem of the institute being responsible for disciplining its members at the same time as promoting their interests.
Some in high places within the organisation seem to think this issue is old hat, but many members of the profession are uneasy about the subject, citing the comparatively lenient punishments meted out to Michael Jordan and Richard Stone, the Coopers & Lybrand insolvency specialists, over their Polly Peck conflict of interest case.
Others worry that the years spent investigating affairs such as Barlow Clowes threaten the organisation's standing as a regulator. And last week's council meeting demonstrated that the matter was alive and well in its upper echelons.
Under discussion was a plan introduced by Ian Plaistowe, president of the institute last year and now chairman of the professional conduct directorate, designed to allay fears that a request for advice or guidance could lead to an appearance before the bench on a professional conduct or practice regulation charge.
Mr Plaistowe wrote in a cover note on the proposals that those responsible for providing the advisory and guidance services could not recall 'a single instance in which it has been necessary for such a report to be made, but that does not mean the fears are groundless or unreal'.
As a result, it was proposed first to make ethical support services separate from the professional conduct directorate - a change to be marked by 'the physical removal of staff and the erection of real (not Chinese) walls'.
Second, there was a plan to exempt members of the institute and employees of the secretariat who provide ethical advice to members from the duty of reporting misconduct.
It was emphasised that this did not affect the discretion enjoyed by every citizen to report to the proper authorities crime and similar serious misconduct.
The separation of ethical support services from professional conduct had an easy enough passage. The only real challenge was a suggestion that the new body would be truly independent if moved outside the institute itself.
However, Jock Worsley, chairman of the Chartered Accountants' Joint Ethics Committee - the body to which the new department will report - told members that ethical guidance and advice was very much tied up with the institute.
To take responsibility for this area away would be 'an admission of failure', he said.
More problematic was the exemption from the duty to report misconduct - and not for the reasons that might be thought.
Rather than worrying about how such a change might look to those outside who have accused the profession of lacking vigour in dealing with the failings of individual practitioners, many members were concerned that the proposed exemption did not go far enough.
In particular, Maurice Ede, a sole practitioner, seemed to strike a chord when he said the line between ethical and technical advice was difficult to draw. While backing the planned change, he brought up the issue of perceptions - saying that people did not believe that walls between the institute's various departments existed. Consequently, there was a danger that a well-intentioned inquiry could lead a member into trouble.
What would happen, it was asked, if somebody phoned up saying they had a technical query and were therefore directed to somebody in that department, but it turned out that the problem was really ethical? Would the technical person feel obliged to report the matter?
Efforts were made to reassure members that such a situation would not arise since the real nature of the inquiry would be spotted in time.
Meanwhile, representatives of the big firms, such as Price Waterhouse's Graham Ward and Touche Ross's Ken Wild, were less circumspect. Mr Ward said there was an 'urgent need' for the change, while Mr Wild said he could not imagine a situation where a request for technical advice could lead to disciplinary action.
But this divergence of views has a lot to do with the distinctions among the firms themselves. While the likes of PW and Touche have extensive back-up teams offering help on technical and other issues, smaller firms are - in the words of one member - living in an increasingly complex world, where such developments as FRS3 could cause confusion and misunderstandings.
Although the fact that the institute's ethical advisory services deal with about 12,000 inquiries a year does not suggest a general reluctance to come forward, there seems to be a widespread feeling that the numbers might be much higher if there was some exemption.
Here, of course, is the dilemma. If members do not feel that they are getting the right kind of service from their professional body they will consider it to be failing in its trade association role. But if that same body does not work hard to maintain its members' standards it will be seen to be falling short of its responsibilities as a regulator.
The proposal was eventually accepted. But not before Ian Hay Davison, one of the most respected members of the profession, made a contribution guaranteed to jolt anybody there complacent enough to feel that events had reached a satisfactory conclusion.
The debate had epitomised the problem of not addressing the question of whether the institute is a regulator or a trade union, he said. This was the 'inherent conflict that we continually refuse to face'.