If it can be proven that an accuser actually lied and she (or he) then they aren't a victim, everything turns on it's head and the accused is now the victim, the victim is now the accused and she/he deserves to be prosecuted.
Thankfully such scenarios are rare but they do happen and the effect...
Sadly it's far more prevalent than people imagine; a close relation of mine was raped by two boys when she was 15. At the time she was afraid that she would get no support from her parents and would likely get blamed for "getting herself into that situation". So she decided not to go to the...