Michael Froomin says I was wrong to say that it would require an act of civil disobedience for a member of congress in possession of secret information about illegal activity to disclose it, since a member in such a position could use the privilege contained in the "speech and debate" clause to disclose what needed disclosing. My general sense is that the speech and debate clause is one of those things prone to misinterpretation by laypeople, but Froomkin's a law professor so presumably he knows what he's talking about.
In a larger ethico-political sense, presumably the purpose of congressional briefings on classified matters is precisely that if the veil of classification is being used to obscure illegal conduct the briefed member will act to disclose and/or halt the conduct. In practice, the function of the briefings seems to have become ensnaring members in complicity while granting them a pretext for not doing their job ("I knew, but it was secret!). But this makes no logical sense. If members of congress aren't supposed to speak up when they become aware of secret crimes and abuses of power, what's the point of them having them in the loop in the first place?