Obviously, this is hardly worthwhile unless the situation is fairly serious.
We may not know that things are "serious" until it's too late to keep our mouths shut.
A chain of small, seemingly innocuous statements could turn a simple traffic stop from being let go for a warning to something much, much worse, especially if there's a bit of bad luck involved. There's a huge amount of officer discretion involved, but if the officer is ambitious or under pressure to meet certain performance goals, it can be easy to take advantage of opportunities that your words open up. This is a totally worst case hypothetical, of course, but imagine a traffic stop conversation like this:
cop: Do you know why I pulled you over, sir?
you: Well...yeah, I know I was speeding back there, officer. I'm really sorry. But it's downhill there, y'know. (you just admitted to speeding). (You're pretty nervous and you get talkative when you're nervous) But look, it's halftime for the Super Bowl and we ran out of beer so I was in a rush to go on a beer run and get back in time for the second half. It was just a quick drive to the store.
cop: Yeah, I can't believe our team is in the Super Bowl either. So, how many drinks have you had, sir?
you: Oh, just a couple, officer. I'm a real lightweight. I can't drink a case of beers each like some of my buddies (you just confirmed you've had alcohol and low alcohol tolerance)
cop: Sir, would you mind stepping out of the car. I would like to perform what's called a field sobriety test. It's just routine.
you: Really? Oh, OK, officer.(You can't be forced to do the sobriety test in your hypothetical state, although other consequences are triggered automatically by refusal)
You were never the coordinated, Dancing With the Stars type anyway, but with a couple beers in you, you fumble with one of the tests. You're really nervous now and that just makes you tense up and fumble even more, but you get through it OK after a couple tries. (You think you're safe because you finally passed the test cleanly, but the fumbling was caught on the cruiser video camera in case you're charged with DUI)
cop: Sir, I'd like to take quick look in your vehicle. That would be all right, wouldn't it? I mean, you don't have anything illegal, right?
you: Oh...well...
cop: Look, we can get this over with quickly or we can stand out here in 30-degree weather for an hour while I call out the K9 unit. You're going to miss the rest of the Super Bowl.
you: Oh...uh...OK. It's not like I'm hiding anything, officer. (you just gave consent to a search of your car)
So the officer proceeds to look in your car and finds a small bag of marijuana on the passenger side floor. "Darn it, that dumb pot smoking brother of yours must've dropped it when you gave him a ride yesterday!" you curse under your breath.
He proceeds to look in the trunk and sees the handgun case. You totally forgot you still had that in the there.
You were target shooting at your friend's farm just over the state line from your house last weekend where it's legal to have a loaded weapon in the trunk--but not here. You inherited that gun from your late father when he passed away a few years ago. Guns don't need to be registered in his state but they do in yours but you were lazy and never got around to registering it. So now the officer is looking at an illegally loaded, unregistered handgun in your car.
cop: Sir! Put your hands on the hood of the car. I'm placing you under arrest for...
Sounds fantastic, I'm sure, but any one of these slips of the tongue could get anyone into a jam they might've avoided, and they do happen to someone out there every day, I'm sure. As I was remarking about Izzy's statement, police don't have to lie to get you to incriminate yourself. We are often our own worst enemies, legally speaking.
I don't mean to write this as a bash on police. Look, to the officer, he has a case that you're some drunk driving, pot smoking douche bag that drives recklessly fast around town with a loaded, unregistered gun. You need to be taken off the streets before you kill someone with that car or that gun!
Geez, looking at this post I just wrote, I sound like an ACLU lawyer...