I understand the value of virginity on a personal level, but the point is it's very, very difficult to prove medically. Far harder than most people realise. Consider these findings...
In a study of 26 pregnant adolescents who reported sexual abuse, 22 participants (64%) had normal or nonspecific genital examination findings, eight (22%) had inconclusive findings, four (8%) had suggestive findings, and only two (6%) had findings of definite evidence of vaginal penetration.
In a case study involving 192 sex abuse victims and 200 virgins, presence or absence of 21 different hymenal or vulvar features was compared between the two groups, such as presence of hymenal tissue, transections, perforations, and notches. It was found that only 2.5% of physical exam findings were unique to the group with a history of penetration.
In a study of forensic physicians in Turkey, 66% of respondents reported that their findings from at least one virginity exam contradicted a recent virginity exam of the same patient.
In the US, 137 pediatric chief residents were asked to identify the hymen on a photograph of pediatric anatomy; only 64% were able to correctly identify the structure.
If 64℅ of senior doctors are unable to identify it, what hope does a police officer, a prison warden, a nurse or (heaven forbid), a groom's mother have of getting the diagnosis correct?
(A systematic review of 1269 independent studies on virginity testing).