Parents start serving 27 months for serving alcohol at son’s 16th birthday party

The Washington Post in this editorial, and David Bernstein here at The Volokh Conpirary, are justifiably spotlighting the apparent injustice in this story of two parents given 27-month(!) jail terms for having provided beer and wine at a backyard birthday party for their son when he turned 16. 

According to the Post editorial, the prosecutors “originally sought a three-month sentence,” but apparently a juvenile court judge “originally imposed eight-year sentences” only an appeals court cut the sentence to the 27 months now to be served.

Commentors at Volokh indicate that the parents’ wrongdoing went beyond just serving alcohol.  But, geez, wouldn’t the three-month sentence (or even six months or nine months) sought by prosecutors have been sufficient?  I have long thought that any sentence more than twice what a prosecutor requests should be considered presumptively (though not per se) unreasonable. 

More details about this case and related matters are available in this cover article from a publication called “The Hook.”  The article spotlights that the long sentence given to the parents should have a profound deterrence effect, though I’d think a shorter sentence could do the trick.  Can anyone suggest reasons why such a long jail sentence is necessary under these circumstances?