Welcome to Free Republic. I would suggest you begin carrying a very compact and cheap recorder with you. It seems like a really good idea to be able to record any conversations you may be surprised by.... ie secret service. Especially hostile SS, as the woman who wouldn’t give you her card seemed to be.
They can be purchased for around 50 bucks. You don’t have to stick it in their faces, just subtly turn it on and hold it.
[I would suggest you begin carrying a very compact recorder]
That was my very first thought while reading through the article. The only way they could prevent you from using it would be by force and then you’d really have a case against them.
I believe it is legal to record if they know you are doing it.