My understanding is that an oath was required by the Intel Committees after Leaky Leahy but I am still researching to find out. I will call an aide tomorrow and ask if I cannot find out.
AFTER Leahy! Why am I not surprised? LOL.
I made a couple of calls, too, and the response was interesting...'well, I'm SURE it's an oath...well, I THINK it's an oath...well, I'll check'.