Bias and Conflict of Interest in Adjudicators . Scope of this Topic
Of these two issues, bias (properly 'reasonable apprehension of bias') and conflict of interest, bias normally only occurs in relationship to either judges or tribunal members (ie. adjudicators). Conflicts of interest however can occur in any relationship where another person (including an adjudicator) owes you some sort of various duty (loyalty, impartiality, honesty, etc). There is active law on conflict of interest with respect to the professions generally, especially lawyers: Representation - Lawyers - Conflict of Interest.
The scope of this present topic is however only in relationship to adjudicators - ie. judges and tribunal members. It's also mostly dealing with issues of bias as conflicts of interest tend to be openly known and subject to public scrutiny, resulting in self-recusal before it gets to litigation.
As you will see from reviewing the case extracts, the definitions offered by the courts for bias are inherently vague [here's a sample: "... what would an informed person, viewing the matter realistically and practically — and having thought the matter through — conclude."]. As well, when either conflict of interest or bias occur in a case, the task of identifying them often suffers due to a lack of clear-cut knowledge of the facts. Also it is often in situations where the client is vulnerable - either situationally, financially and in terms of knowledge - and so less able to dispute their presence.
My view is however that simple lay definitions will suffice. Issues of 'reasonable apprehension of bias' occur when - for whatever cause - there is justified suspicion that the adjudicator is going to be prejudiced against you because of who you are. That is, bias issues emanate from something intrinsic to the client as a class - race, politics, gender, sexuality and more.
On the other hand, issues of 'conflicts of interest' arise - not because of who you are - but because of the situation that your legal case arises in. That is, conflicts of interest emanate from something intrinsic to the situation, which here is the case. An adjudicator 'guilty' of a conflict of interest doesn't have to have anything against you necessarily, it's that the case situation gives rise to incentives for the adjudicator to favour other interests.
An example of a conflict of interest would be a lawyer with a pre-existing client A - whom legally and ethically they owe a duty of loyalty to - allowing themselves to be hired by another client B whose interests conflict with those of client A - but who is far richer and offers the prospect of more lucrative work.
In a very real sense, 'conflicts of interest' arise out of factors entirely unrelated to you, while 'bias' arises out of factors entirely intrinsic to who you are.
. The Underlying Issues for Both is Partiality
As a rough rule, conflicts of interest tend to be financial in nature, while bias motivations tend to be more personal. But what both bias and conflict of interest as issues share is that they compromise the 'partiality' of the adjudicator - their independence from the case. Thus you will see how much this law speaks of a 'presumption of impartiality'.
. Recognize the Litigation Reality
Given the intense nature of conflict and bias as issues (money and personal identity), it's no surprise that feelings often run high when the suggestion of them arises. When such issues arise, they normally involves all of: (1) the central interests of a client who is entitled to impartiality, (2) the suggestion of deception on the adjudicator's part, (3) the reputational effect on the adjudicator if the allegation is made out, and (4) the natural lack of objectivity that litigation parties tend to have about the strengths of the legal merit of their cases.
These presence of these factors are a veritable recipe for tension. When an adjudicator renders a decision contrary to the interests of a party - a party who has 'all along' harboured (or even voiced) suspicions of the adjudicator's lack of impartiality - it's not surprising to see that leading the way in grounds of appeal is 'bias' [and less so (as explained) that of 'conflict of interest'].
This reality is shown to be true on a moderate observation of the courts, with bias grounds of appeal ranking high in occurence, but with only low ranking in success. Like appeal grounds of 'inadequate reasons', or 'ineffective assistance of counsel', these grounds are inherently vague and thus easier to plausibly allege. It's fair to characterize such appeal grounds as often being the 'last resort' of the desperate litigant, or the unscrupulous lawyer (or both).
That said, bias and conflict of interest do sometimes succeed as appeal grounds. There are at least two successful cases in the present case-extract collection at the time of writing. So they're not hopeless law, but they are close to it.
In my opinion, this low-success rate on appeals is not due to judges culturally 'sticking together' in solidarity, but to the reality that bias and undeclared conflicts of interest are truly unusual and - to the extent that they do occur unremedied - their survival is due to the much larger problem that the poor and un-legally-schooled amongst us face in advancing any legal cause: see Democracy, Law and Duty.