For some interesting stuff about a US Citizen's almost-never-exercised right to remain silent when re-entering the United States, and the punitive responses it incites from our public servants, see Paul Karl Lukacs, I Am Detained By The Feds For Not Answering Questions and the sequels, 10 Brief Responses To 700 Comments About Refusing To Answer Questions At Passport Control and More Law: Refusing To Answer Questions At U.S. Passport Control.
Here's how it begins:
I was detained last night by federal authorities at San Francisco International Airport for refusing to answer questions about why I had travelled outside the United States.
The end result is that, after waiting for about half an hour and refusing to answer further questions, I was released – because U.S. citizens who have produced proof of citizenship and a written customs declaration are not obligated to answer questions.
* * *
“Why were you in China?” asked the passport control officer, a woman with the appearance and disposition of a prison matron.
“None of your business,” I said.
Her eyes widened in disbelief.
Lawyers and others may want to read Split Circuits, N.D. Georgia Notes Split Re: Whether Use of Pre-Arrest Silence in Government’s Case-in-Chief Violates Fifth Amendment
(Found via Pogo Was Right, Pointer: More Law: Refusing To Answer Questions At U.S. Passport Control)
Yes, it's what I ordered….but it's defective. One of the major features just doesn't work. 
This is definitely hopeful:
