[I]f a teacher instructs any student aged 16 or younger how to utilize contraceptives under circumstances where the teacher knows the child is engaging in sexual activity with another child--or even where the "natural and probable consequences" of the teacher's instruction is to cause that child to engage in sexual intercourse with a child--that teacher can be charged [with contributing to the delinquency of a child.] The teacher need not be deliberately encourage the illegal behavior: he or she only need be aware that his or her instruction is "practically certain" to cause the child to engage in the illegal act. Moreover, the teacher could be charged with this crime even if the child does not actually engage in the criminal behavior. Depending on the nature of the child's behavior, the teacher could face either misdemeanor or felony charges with maximum punishments ranging from 9 months of jail to up to six years of prison.
If it weren't so despicable, Southworth's transparent threat would be amusing. Later in the letter he warns that the new guidelines "may expose your district to civil litigation." This is so not only because parents will sue for the "sexual assault, unplanned pregnancies, sexually transmitted diseases, emotional trauma, etc." that will inevitably result from learning how to use contraceptives, but also because "the ACLU of Wisconsin has previously made it clear that it wants to monitor sex education programming in Wisconsin Schools."
Beautifully, it is Southworth himself whose conduct has most likely bought the taxpayers of Juneau County an ACLU-funded lawsuit. Ordinarily, one can't sue to prohibit a future prosecution. You need to demonstrate a substantial likelihood that you personally will be targeted, and most people can't show that. But when a teacher shows up with a letter in hand from the DA saying "if you follow the new state law I will put you in jail," I think she's going to get her day in court.