The context in the verses, above, is about one person accusing one other person. Even though the accusations may be true, the accusing in the absence of the second witness constitutes false witnessing against ones neighbor. That is, James is condemning the accusations of the "one-on-ones." The Law of Moses demanded that at least two witnesses accuse the third party, because in such cases the problem would not be confined to one person against another, but against the collective interests of the wider communitythe problem would not be confined to one person against another, but against the collective interests of the wider community.