For many years, I've followed a lot of stories about law enforcement, privacy issues, and your rights. After seeing how law enforcement in the USA works, I think it's quite important for EVERYONE to know just one thing... From years and years of my own experiences, I can tell you it's the only way to operate.
Do everything by the book. Go through official channels. Volunteer absolutely nothing.
I know it may sound like something you'd hear from a career criminal or a crazy privocy advocate, but I'm neither. It's just how things work in the real world.
For instance... All the time I hear stories of someone who gave their boss an ultimatum. Perhaps their boss is doing something illegial, immoral, or just in conflict with company policy. What inevitably happens, is that their boss swears he will repent, and change his evil ways. This only serves to placate the complaining employee, and keep them from complaining through official channels. While that's happening, their boss is very busy, scheming to counter the threat. What they do is what the employee should have done... The boss goes through official channels, filing complaints against the employee, claiming anything from harassment to incompotence. In one instance, I've even heard of a boss later telling the employee they can have some time off, but never filing the proper paperwork, and denying that the conversation ever took place. This all culminates in firing the employee, and setting yourself up with a made-up reason the employee might hate you, and be willing to make-up a story to hurt their (former) boss. This obviously could have been avoided if the employee wasn't quite so considerate, and sheepish. If you go through offical channels, this will not happen. Another good lesson in this is that you should not do anything significant, strange, etc., without having it in writing. If you are getting extra time off, make damn sure you have a copy of the request form, or whatever your company happens to use.
What police do really concerns me the most. Whenever they suspect you of doing something illegial, but don't have enough for a warrant, they will try to con you into letting them search. Most commonly they say they'll be nice to you, if you are nice to them. Sounds good in theory, but once they get what they want, you can bet they won't be doing you any favors at all. Less often, I hear about police that ask to search your home or vehicle, saying they don't care about anything illegial you might have, they only want to see if there's someone or something they're looking for. Of course, once you give them permission, and they stumble on to something illegial, they'll take you in. It's probably on their vehicle cameras, but even if it's brought-up in court, the fact is, they can lie their asses off with no consequences. Once you try to help the cops out a little, and volunteer to anything, they've got free reign, and no matter what they told you before hand, they are going to use it.
In addition, there may be built-in privacy or other types of limits in the laws, that don't apply when you are scammed into volunteering. Going back to the house search senario... If you volunteer to let them look through your house for, let's say, a suspect, and they get nosey and decide to look through your dresser drawers, where they find drugs, or perhaps a gun that is not registered in your name (they check gun regs. before they enter your house, of course) then they will take you in on those charges, and everything will be admisible in court. If you did everything by the book, they would have had to get a warrant, and it would have had to specify that they weren't looking for weapons nor drugs, then they couldn't pull tricks like that on you.
Let's cover this by a much different senario. DNA and privacy. Lots of DNA dragnets are happening, so it's a very relevant subject. Let's say you are asked to volunteer DNA, and they threaten to arrest you, or just give you a really hard time if you don't cooperate. Well, the rules are completely different if you volunteer. If they go through the trouble of getting a warrant, then force you to give DNA, there may be rules in your locale that don't allow them to check those results against any case other than the one specified, and prevent them from revealing that DNA info to anyone. Lots of people are concerned that their insurance company will find out that they are pre-disposed to develop a certain disease, and silently revoke their coverage. It's a very real threat, since there have been cases brought to court of it happening.
Protesters are being forced to get smarter about their rights, because police have been very sneaky. They can ask you for your name, or more often ask for ID, and then find out if they can put together any reason to arrest you. You have no reason to give them your name, unless you were pulled-over while driving, or after you've been arrested. Before then, just say no, or even make-up a name... It is your right. I've never been a protestor, but around here, it's not too hard to be in a bad place, and look suspicious. I've had cops ask me for ID. I happily shake their hand, and introduce myself, by first name only. They can be persistant, but you don't have to give them anything. Even if you give them your ID only because they said they'd arrest you otherwise, they were lying, and you just volunteered information. Now, you migh be arrest for something as simple as an unpaid speeding ticket.
Volunteering for anything only does bad things to you, and never anything good. No matter what anyone promises you, don't believe them. Go by the book, don't volunteer anything.
Even if you aren't a protestor, nor a minority in a white neighborhood, nor look homeless, these are important rules to live by, and you'll get screwed over every time you don't strictly follow them.
Although I have not experienced most any of these senarios, I do directly know people who have, and I've been in less serious situations where I got "the short end of the stick" as they say.
Now, since you might not see how it applies to the situation you are in, let's expand on the rules to live by.
Always go by the book, and follow procedures in-order, and don't skip anything.
Volunteer no information to anyone. Looking or sounding suspicious is no crime.
Get everything REMOTELY important, in writing.
If admitting guilt, be VERY specific about what you did, and what you don't admit doing.
Don't sign anything that you have not read fully and very carefully. Be very supicious of pressure.
There is no such thing as a "standard form", you are going to get screwed if you just sign.
Even if someone sounds like they are trying to be nice, be VERY skeptical of their good intentions.
I welcome everyone to add their own comments here. Either if you'd like to add to these rules, or have your own experience to share.