How to be a Man of Principle(TM)

Exhibit A: Senator Arlen Specter.
Step 1: First excoriate proposed legislation in no uncertain terms:

Specter said hearings before his Judiciary Committee showed that the military Combatant Status Review Tribunals do not have an adequate way of determining whether suspects are enemy combatants.
He charged that by striking habeas corpus rights for terrorism suspects, the bill “would take our civilized society back some 900 years” to a time before the Magna Carta was adopted. He said this was “unthinkable.”
“What this entire controversy boils down to is whether Congress is going to legislate to deny a constitutional right which is explicit in the document of the Constitution itself and which has been applied to aliens by the Supreme Court of the United States,” Specter said. If the bill passes without habeas corpus protections, it will be struck down
by the high court…

Step 2. Vote for it anyway.
(President Bush as King John? Not implausible…..)