Persons interested in the result of the trial are considered incompetent to give evidence.

From the nature of human actions and passions, and from the fact that all persons, even the most virtuous, are unconsciously swayed by motives of interest, the testimony of such persons is rather to be distrusted than believed.

This rule will, perhaps, be generally of difficult application in masonic trials, although in a civil suit at law it is easy to define what is the interest of a party sufficient to render his evidence incompetent.

But whenever it is clearly apparent that the interests of a witness would be greatly benefited by either the acquittal or the conviction of the accused, his testimony must be entirely rejected, or, if admitted, its value must be weighed with the most scrupulous caution.
Such are the rules that the wisdom of successive generations of men, learned in the law, have adopted for the establishment of the competency or incompetency of witnesses.

There is nothing in them which conflicts with the principles of justice, or with the Constitutions of Freemasonry; and hence they may, very properly, be considered as a part of our own code.