Here are some refferences and thoughts on the matter of fairness within the Buddhas training.
The Buddha often called people fools (particularly in the vinaya directly) not because of them as a person but based on
what they do or have done. This is important to remember regarding fairness, because this principle is spelled out in detail if not explicitly within the vinaya directly, and can be inferred via the suttas which deals with more general principles in this area (of fools).
An origin story in the Mahavaga1.4 translated by T.W. RHYS DAVIDS AND HERMANN OLDENBERG wrote:1. Now at that time the Blessed One walked up and down in the open air unshod. Noticing that, 'The Master walks unshod,' the Elders (the Thera Bhikkhus) also went unshod when they were walking up and down 3. But though the Master and the Thera Bhikkhus went unshod, the Khabbaggiya Bhikkhus walked up and down with coverings on their feet.
The temperate Bhikkhus were annoyed, murmured, and became angry, saying, 'How can these Khabbaggiya Bhikkhus walk shod, when the Master and the Thera Bhikkhus walk unshod?'
2. Then those Bhikkhus told this thing to the Blessed One.
'Is it true, what they say, O Bhikkhus, that the Khabbaggiya Bhikkhus walk shod, though the Master and the Elders walk unshod?'
'It is true, Lord.'
The Blessed Buddha rebuked them, saying,
'How, O Bhikkhus, can these foolish persons walk shod, though (&c., as in §§ 1, 2)..
This is a general example of the Buddha finding something out and clarifying what happened, there are numerous examples of this happening. in essence each rule no matter what it was was never declared to be a breach of the principles unless the Monk had been cross examined and had a chance to give his side of the story. there could of been a misrepresentation of some sort somewhere along the lines, and everyone had the same chance to defend themselves and no-ones word was taken just because of their standing.
When rules were laid down the mendicants were expected to keep them no matter who they were, yet there were reasons the rule maybe innapropriate to keep or the perpetrator was not suitable for the "punishment". The first person whom caused a rule to be set up was automatically immune from the punishment the rule carried as they had no clear cut rule to go by, and the principles although potentially clear could nevertheless be in conflict with other principles due to a form of dissonance. Ven. Sudinna is a good example of this. Through compassion for his mother he was persuaded to engage in sex with his former wife to produce offspring for his parents even though it is clear that he had a knowing of how this was inappropriate from his guilt from engaging in the act (see the Introduction to the BMC1).
essentially, and cutting a long story short, the Buddha didn't EXPECT someone to keep something not laid down in plain sight, and everyone was equal in the vinaya with attainment or anything else didn't give someone more power in a vinaya situation than another (prosecution v' defence).
The Buddha can be said to of walked his talk, and not doing so or attempting to do so (i.e. living the mendicant life when one has taken it up) for any reason - other than situational specific allowances accounted for in the non-offense clauses - brings about critisism from the Buddha (even if they are Arahants).
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He who knows only his own side of the case knows little of that. His reasons may be good, and no one may have been able to refute them.
But if he is equally unable to refute the reasons on the opposite side, if he does not so much as know what they are, he has no ground for preferring either opinion …
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He must be able to hear them from persons who actually believe them … he must know them in their most plausible and persuasive form.
John Stuart Mill