Here's an interesting read on returning to the US from China, and how Paul Karl played around with Customs by refusing to answer questions that did not require an answer, and maintaining his rights as a citizen. I enjoyed it, not a lot of commentary needed besides its worth reading the whole thing.
Knife Tricks Blog:"“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.
“Excuse me?” she asked.
“I’m not going to be interrogated as a pre-condition of re-entering my own country,” I said.
This did not go over well. She asked a series of questions, such as how long I had been in China, whether I was there on personal business or commercial business, etc. I stood silently. She said that her questions were mandated by Congress and that I should complain to Congress instead of refusing to cooperate with her.
She asked me to take one of my small bags off her counter. I complied.
She picked up the phone and told someone I “was refusing to cooperate at all.” This was incorrect. I had presented her with proof of citizenship (a U.S. passport) "