No doubt, most people have read a novel set in a foreign country, or watched a movie to which the action is in a foreign country, to which at some point in the novel or movie, one of the characters is asked for their "papers" in order to confirm their identity for the authorities, with failure to do so, leading invariably to their arrest or detention. For those not in the know, you might think that laws like that don't exist in America, but in fact, they do. Twenty-four States have so-called "stop and identify laws" which are in essence, the same thing as demanding the papers from a person in the public square. This does not mean in America, that you must or are required to carry some sort of legal identification upon you, 24/7, but it does mean, that should you be stopped by a law enforcement officer and he demands that you identify yourself, not providing such identification, in some form or another,will probably result in your detention, depending upon your particular circumstance and how you handle yourself. It shouldn't be that way, but courts have ruled that as long as the police officer had a "reasonable suspicion" that you may be involved in some sort of crime, that they may indeed demand that you identify yourself, and everyone, I mean everyone, can easily fall into that amorphous category of being under "reasonable suspicion".
The above would strongly imply that America is, in actuality, a police state, because if a man can't simply go about his business, without having to answer to law enforcement officers, who apply arbitrary law to you in order to compel you to identify yourself, you are not truly free. Additionally, it almost doesn't matter in principle what your real Constitutional rights are when you are detained by the police, because if you insist upon using them, such as being clever in your responses to the officer, by asking, for example," if you are free to go or are you being detained," without identifying yourself, the situation almost for a certainty will get worse for you, so that the better part of valor, especially if you have not committed a crime, or know that you don't have a warrant for your arrest, is probably to produce your identification, or to provide actual biographical identification information to the officer, so as to keep the situation from escalating to such an extent that you probably will regret it. Of course, that means, essentially that you are giving in to the police state, but when you are dealing with a legal authority, that also has the means to arrest you, to maim you, or even to kill you, perhaps passive obeisance is your best move.
What stop and identify laws mean for Americans, is that your freedom of movement can be imperiled at any time for virtually any reason, by the very people who have sworn to protect and to uphold Constitutional law. Unfortunately, for you, most police officers, are not Constitutional experts, and certainly aren't interested in debating with you the meaning or the intricacies of Constitutional law, they are, however, quite good at making it quite clear to you, that their requests will, more likely than not, be sanctioned and upheld by the judicial system, and/or the barrel of their gun.