Lew, here’s a website that claims that United States Code, Title 13 (Census), Chapter 7 (Offenses and Penalties), SubChapter II stipulates a $100 fine for not answering some or all questions on the Census.
(Thanks to David for posting what we were all probably subliminally thinking when we saw the menacing threat on the envelope of our census forms.)
UPDATE: After more digging, I finally found where the $5000 fine mentioned in your interview came from. Links to the US Code sections that are cited follow (gee, since it’s written in legalese, it must be just!).
18 USC Sec. 3559
18 USC Sec. 3571
13 USC Sec. 141
13 USC Sec. 193
13 USC Sec. 221
