These “laws” have never been tested in court because they would be squashed there. They are for intimidation purposes only... thus far. Many people refuse to answer any questions or allow census takers on their property. None have been prosecuted, at least by 2000. I worked for the Census in 2000 and in 1988-1990. In training we were told all these things and when questioned about how many people were prosecuted the answer was well, none, but they could be.
Several of my friends from church are working on the census this year. One of them told me Sunday that any form with 3 responses is considered "returned" and is not being followed up upon. That corresponds to what many of us have provided - number of residents, gender and age.