>>Even driving at the limit can get you a criminal charges:
http://www.drivers.com/article/149/ LOL.
Of course the "left lane bandit" (or "right lane bandit" in other Commonwealth locales ;-) ) was breaking the law. And since this pair behaved in a fashion they knew would inconvenience and provoke, they're charged for being deliberately antisocial. In multiple jurisdictions, courts confirm that drivers are not de facto policemen entitled to "enforce" laws by impeding or frustrating others.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1