S6, E14: On Valentine's Day, an Iranian fighter jet accidentally shoots down a British passenger plane--killing 100 people--but C.J. is reluctant to awaken the President even as the hawkish British prime minister considers bombing Iran's nuclear reactors in retaliation. After learning that the passenger jet was mistaken for a U.S. spy plane, Bartlet consults with British ambassador Lord John Marbury (recurring guest star Roger Rees - "Cheers"), and they debate whether a strike is the perfect excuse to destroy the atomic sites or if it would set back reform movements in Iran. Meanwhile, Abbey and C.J. feud over the President's schedule for total rest; Toby and a legal professor try to write a new democratic constitution with representatives of Belarus; and everyone keeps dodging the traditional White House appointment with Miss Universe. Christopher Lloyd ("Taxi," the "Back to the Future" films) guest stars as law professor Lawrence Lessig.