Numbers 5:11-31 is a divinely ordained judicial process for trying a woman suspected of infidelity. In a patriarchal society, this is a grace shown to the woman which helps avoid an extrajudicial proceeding that may unfairly convict her of adultery. The text clearly emphasizes that the verdict comes from God and not humans.
The emphasis of this law would be that the woman would "stand before God" (5:16, 30), implying that the verdict would not come from humans but from God alone. Also, she would not be affected by a mixture of dust and water; the efficiency of the curse of the bitter water would require divine intervention on the part of God and therefore acted as a safeguard against manipulated results and reinforced that the verdict could only be given by God alone. Vindication is the clear default; only divine intervention could render a guilty verdict.
The punishment also seems to be not only for infidelity but also for making a false oath before God (5:16-22). The punishment of future infertility (which in early Semitic culture was quite significant) would not be incurred if the woman admits of her guilt. She only receives the curse if she is both adulterous and perjurious.
As for the man, the trial serves to demonstrate whether his feelings of jealousy are legitimate or not. In fact, 5:14 implies that the jealousy the man will feel is directly from God as a means to exact justice if his wife is indeed guilty of adultery; however, if she is innocent, the pangs of jealousy stem from the man himself. The trial is meant not only to try the woman's innocence but also the man's suspicions.
5:31 also implies condemnation for the man if his wife is innocent. His status of being 'free of guilt' is only applied after it has been demonstrated that she indeed is guilty of adultery. If the trial shows her to be innocent, the man is not free of guilt. Thus the man ought not to be zealous to charge h