I have learned that one thing you can predict from members of the Bush-Cheney administration is a total lack of remorse. In Jay Bybee, you have an almost classic case from Hannah Arendt: a mild-mannered creature of the Republican establishment, trained into supine subservience when dealing with executive authority, and able to compartmentalize anything in his own mind to please his superiors and bask in the warm embrace of the institutional, ideological right. So even though he allegedly privately described his lawyering in matters “so awful, so terrible, so radioactive” they would never be uncovered, he gave Cheney everything he could possibly want, and more. As to his "good faith," I believe, from reading his execrable memo, that the only good faith he showed was in finding ways to give his political masters anything they wanted.
Let me give a simple small example, helpfully laid out here. Bybee was able to defend waterboarding as non-torture in a legal memo ostensibly providing objective analysis of the case history of the torture technique in the US. Among the obvious precedents for such a decision was the most recent case - when the Reagan administration Justice Department prosecuted a Texas sheriff and his deputies for waterboarding a suspect to get a confession in 1983:
At the trial of the Texas sheriff, Assistant US Attorney Scott Woodward said the prisoners who were subjected to waterboarding were not "model citizens," but they were still "victims" of torture. "We make no bones about it. The victims of these crimes are criminals," Woodward said, according to a copy of the trial transcript. One of the "victims" was Vernell Harkless, who was convicted of burglary in 1977. Gregg Magee, a deputy sheriff who testified against Sheriff Parker and three of the deputies said he witnessed Harkless being handcuffed to a chair by Parker and then getting "the water treatment."
"A towel was draped over his head," Magee said, according to court documents. "He was pulled back in the chair and water was poured over the towel." Harkless said he thought he was "going to be strangled to death," adding: "I couldn't breathe." One of the defendants, Deputy Floyd Allen Baker, said during the trial that he thought torture to be an immoral act, but he was unaware that it was illegal. His attorneys cited the "Nuremberg defense," that Baker was acting on orders from his superiors when he subjected prisoners to waterboarding.
The Reagan Justice Department - back when Republicans opposed torture - did not buy this defense and neither did a jury. They convicted the the deputy on three counts of civil rights and constitutional violations. Now: this case occurred before the UN Convention on Torture went into effect, but any good faith legal memo explaining the history of this particular torture technique would surely have cited it. It's easily findable with Google, let alone with the research resources available to the Office Of Legal Counsel.