[tomp]

Hm... plenty of men have been publicly accused of rape by women (Duke lacrosse case, the Mattress Girl, Rolling Stone "Rape on Campus", to list a few). I don't recall any legal repercussions for those women. I'm guessing that's because it's really hard to prove they're lying (even though in many cases there is very obvious evidence that they were), but this fact doesn't really support your claim that calling someone a rapist ever results in legal consequences (let alone criminal consequences).

[dragonwriter]

For one rather well-known case of non-criminal legal consequences: https://en.m.wikipedia.org/wiki/Tawana_Brawley_rape_allegati...

Discussion of criminal recourse (and considerations involved in pursuing it, from prosecutors' perspective) is here (starting on p. 8): http://www.ndaa.org/pdf/the_voice_vol_3_no_1_2009.pdf