Translations:Does Joseph's intent to divorce Mary show that the death penalty for adultery was not mandatory?/20/en

This case is describing a legal action brought by the parents of the girl against the man's public slander. The parents are able to prove the husband's slander by the use of the "evidences of virginity" (possibly a blood-soaked garment). The lack of such evidence does not prove the girl's guilt -- it's lack would simply prevent the parents from challenging the husband's slander, in the first case. The separate case cited in verses 20-21 would require the husband to bring at least two witnesses against the girl (in accordance with Deut. 19:15) and would result in a mandatory death penalty (v. 21), not simply divorce.